Charlize Theron says her "free time" is devoted to her son.
The 'Million Ways to Die in the West' actress gave birth to Jackson two years ago and admitted becoming a mother has been a "natural" change for her.
She told the Mail on Sunday newspaper's Event magazine: "It's a beautiful change, one that is completely natural.
"Obviously, Jackson is my priority now. If I have free time, he's the one who gets it.
"Not because I have to, but because I can't wait to be with him. He gets to be the number one in my life."
The star - who started dating Sean Penn in February - also revealed her and ex-boyfriend Stuart Townsend's son has given her the chance to go back to her dancing roots after an injury cut short her professional ambitions.
She said: "I still dance in my living room every day. I have a lot of 'Mama, let's dance!' going on in my house right now."
When she's not relaxing with her family, Charlize said she enjoys getting time to herself during filming because it lets her catch up on music and books she might have missed.
She added: "I always love when I'm on location and I have that bit of trailer time to myself.
"I'm constantly sharing stuff with my friends and that's predominantly how I get my music. I recently played Pharrell William's album, which I thought was really great.
"And I love reading. I just re-read 'Outliers' by Malcolm Gladwell, the book about statistics and looking at numbers, and the coincidence - or it's not a coincidence - that birthdays play a role in success. It's fascinating."

Mariah Carey couldn't have coped with her twins "without extra help".
The singing sensation insisted she doesn't want to miss a moment of her daughter Monroe and son Moroccan, both three, growing up, but admitted she was glad to have people to support her.
She told the Sunday Mirror newspaper's Notebook magazine: "Every little bit of a child's life counts, every memory, every moment. I can never have this time back.
"But it's a luxury to be able to have someone there. I don't know how people do it - I was breastfeeding in tandem.
"I did everything I could, but I couldn't have done this without extra help. I'm grateful. I have two people who help a lot."
Meanwhile, Mariah revealed she doesn't live out her diva image at home, but joked her daughter outshines her in that regard.
She added "I'm always in sweatpants. But I may wear a high-heeled pump with them ... A slipper with a puff.
"I have so much fun with Miss Monroe, as I call my daughter, and she is - even though we don't like to use this word - a natural-born diva, darling.
"She walks in my heels, she's in my lingerie closet. She has me beat by a mile."

Lea Michele has posted a touching tribute to late boyfriend Cory Monteith on his birthday today (11.05.14).
The 'Glee' star described the actor, who died in July last year of a drug overdose, as having "the biggest heart and most beautiful smile" and shared a photograph of the pair together.
The black and white image, posted on Lea's Twitter page, shows the couple sharing a joke, and she accompanied it with the caption: "The biggest heart and most beautiful smile.. In all of our hearts.. We love you so. Happy Birthday. (sic)"
Fans showed their support for Lea and claimed they too were still "heartbroken" over the actor's death.
One wrote: "This photo broke my heart. i miss him so much. Stay strong love i love you. Happy birthday angel Cory. (sic)"
Cory, 31, who starred in 'Glee' with Lea, was found dead in his Vancouver hotel room just months after checking himself into rehab for substance abuse.
A friend close to the star claimed he was "healthy and in great spirits" just two days before he passed away.
Lea, 27, previously spoke about her boyfriend's death at the Teen Choice Awards.
She said: "He was very special to me and also to the world. And we were lucky to witness his incredible talent, handsome smile and his beautiful, beautiful heart.
"So whether you knew him personally or just as Finn Hudson [in 'Glee'], Cory reached out and became a part of all of our hearts - and that's where he'll stay forever."

Selena Gomez is trying to "erase" Justin Bieber from her life.
The 21-year-old pop star, who has had an on/off relationship with the 'Boyfriend' hitmaker for a few years, is reportedly attempting to forget the 20-year-old singer so she can move on with her life.
According to HollywoodLife, while Selena was shooting her Adidas Neo commercial in New York City last month, she asked for all traces of Justin to be removed from her working environment and didn't even want to say his name.
A source said: "A few of the camera guys names were Justin and her team asked [if] their names be changed so she didn't have to say the name Justin."
The request came just a few days after the pair were spotted hanging out together in McAllen, Texas, before going to a dance studio to rehearse.
Meanwhile, Justin has been linked to a number of beauties, since the pair reportedly had a "huge fight", including 18-year-old model Yovanna Ventura and Selena's friend Kylie Jenner.
But Selena isn't bothered by the rumours and claims Justin can date whomever he likes.
A source added: "If he wants to date [a] teenager like Kylie or a wannabe model, then let him. She's done and moving on from the broken promises and drama."

Britain's Eurovision Song Contest entry Molly Smitten-Downes came in 17th place on Saturday night (10.05.14).
The previously unknown 27-year-old singer performed her self-penned song 'Children Of The Universe' dressed in a stunning dress and received 40 points from voters in 26 countries.
British voters gave their highest score of 12 points to Austria's entry, drag queen Conchita Wurst, who went on to win the competition.
She is known as the country's "bearded lady" and sang 'Rise Like A Phoenix', claiming: "We are unstoppable", as she collected her award on stage.
Although Mollie missed out on the top spot, she had plenty of support on Twitter with followers describing her performance as the "best song of the night".
One fan wrote: "Downloaded the song straight away. It's fair to say you've done the UK proud! stunning voice. Be proud of yourself. (sic)"
Ahead of her performance, Molly thanked fans on Facebook, writing: "Just want to say thank you from the bottom of my heart to all of you. I am amazed everyday by your kindness, support and encouragement. I am so so grateful to be heading onto that stage singing a song I believe in so much.
"I'm gonna sing it like I mean it, because I do, every word. I hope you feel it wherever you are! Now enjoy the party! HERE WE GO!! (sic)"
The Netherlands came in second place in the Eurovision Song Contest, while Armenia came in third in the competition.

Chris Martin was "hard to live with" before he split from Gwyneth Paltrow.
The former couple - who have children Apple, nine, and Moses, eight, together - split last month after 10 years of marriage, and insiders claim the Coldplay frontman's insecurity caused a lot of their problems.
A source told Britain's Grazia magazine: "Chris is very tough on himself and that can be hard to live with. There was a time a few years ago when there were a lot of fights.
"He and Gwyneth had a great life but it was like he couldn't quite see it and couldn't commit to it. There were other issues that sparked off that and, ultimately, they ended up leading very different, very separate lives."
Now they have gone their separate ways, Chris and Gwyneth both want the best for one another.
The source added: "They have both given each other their blessing to move on. I think they both want each other to find love and happiness."
The 'Magic' singer recently admitted his own "issues" had stopped him from being happy.
He said: "If you can't open yourself up, you can't appreciate the wonder inside. So you can be with someone very wonderful, but because of your own issues you cannot let that be celebrated in the right way....
"About two years ago I was a mess really because I can't enjoy the thing that we are good at and I can't enjoy the great things around me because I'm burdened by this - I've got to not blame anyone else and make some changes."

Courtney Love says the 20-year anniversary of Kurt Cobain's death has been "deep".
The Hole singer met up with her late spouse's former Nirvana bandmates Dave Grohl and Krist Novoselic as the band were inducted into the Rock and Roll Hall of Fame at Brooklyn's Barclays Center recently, one of their first meetings in years, and she found it "cathartic" to see them so long after her husband committed suicide.
She explained: "The recent 20-year stuff has been really deep.
"Its been really good, though. I hadn't seen Krist [Novoselic, Nirvana bassist] or Dave [Grohl] for 20 years! We were supposed to have meetings every month, but they never happened. I think we had a phone call once in, like, 1997! Seeing them was cathartic and really lovely."
Courtney admits the bitterness between them has fizzled out and she is glad they're have a better relationship now.
She told Kerrang! magazine: "It's amazing that we could take two decades of slagging each other to the most extreme degrees and be done with it in one night.
"I think Dave's a class act, I think I'm a class act and I think Krist is a class act. It's a testament to the memory."

Carey Mulligan loves working in London.
The 28-year-old star - who is married to musician Marcus Mumford - has returned to her hometown to film her new movie 'Suffragette' with Meryl Streep, and to star alongside Bill Nighy in 'Skylight' and she's confessed it's refreshing to see her family after a long day on set.
She said: "I'm really happy to do something in London. And to go home to my house every night, and see my friends and family, and have people who never usually get to see me on stage see it. There's something about doing it in a hometown that feels a bit special."
The 'Inside Llewyn Davies' actress - who has starred alongside heartthrobs Ryan Gosling in 'Drive' and Leonardo DiCaprio in 'The Great Gatsby' - is excited to make her return to the stage after seven years in such a beautiful theatre.
Quizzed on what she thinks of the theatre where 'Skylight' will open next month, she told Britain's Vogue magazine: "It's one of those places that's so magical. The Wyndham is the kind of theatre that just speaks to the seven-year-old girl in me. I imagine there'll be light bulbs around the mirrors in our dressing room."

The Vamps drummer Tristan Evans says streaking is a "daily occurrence".
The 'Wildheart' singer says he regularly strips down to the nude for shower trips in front of his bandmates, Bradley Simpson and James McVey, however Connor Ball is more likely to bare all in public as he has a "better body."
Tristan exclusively told BANG Showbiz: "It's probably more James actually because he has the better body. I will get naked eventually. I think it's a daily occurrence, I think last time, Brad was the one who got pretty naked. We're comfortable with our personalities and bodies and, you know, we just have a good time."
Despite baring their bottoms, the 19-year-old popstar insists their manhoods are "always covered".
Meanwhile, Tristan recalled on the time he did have to get his manhood out to urinate in public in a desperate bid to relieve himself when there were no toilets available during their long coach journey on tour.
He explained: "[Once I had to pee] in the hedge outside the service station. The awkward thing was it was right next to a huge billboard advertisement so everyone was looking at the board and then looking to the left and there's a dude peeing in the hedge, it was really weird."

Katie Price still wants Kieran Hayler be at the birth of their child.
The former glamour model - who split from her husband earlier this week after finding out he had an affair with her best friend - is said to be scared about becoming a mother for the fifth time and she doesn't want to be alone when she gives birth to their second baby.
An insider told The Sun on Sunday newspaper: "Katie is terrified about the birth and despite everything that has gone on, still wants Kieran there.
"He's been a fool but it's still his child and she doesn't want to go through childbirth alone.
"Jett's birth was a traumatic experience so there's no chance she wants to go through that on her own."
According to reports, Katie found out about Kieran's affair with Jane Pountney after she saw them kissing on a beach, before getting confirmation after seeing a message on his phone saying: "Has she left yet? Can't wait to see you."
A source added: "Katie was furious about the kiss in Cape Verde on what was meant to be a romantic break for her and Kieran - their first with baby Jett.
"They fobbed her and [Jane's husband Derrick] off, claiming it was a drunken snog, but Katie didn't fall for it ... Then she saw the Whatsapp message on Tuesday - that's when she exploded.
"She was furious and knew immediately that the affair was long-term and sexual. She confronted Kieran who confessed all. She could have forgiven them for a kiss, but not for a full-blown affair."
Meanwhile, Jane's husband Derrick has reportedly asked Katie not to cash-in on on their heartbreak.
A friend told the Sunday Mirror newspaper: "Derrick has been begging Katie not to go ahead and speak out with more details about his wife and Kieran.
"He has already been left brokenhearted over the fat that news of the affair has come out.
"He understands Katie is angry but if she gives an interview it will cause more hurt for everybody involved in this torrid situation and certainly won't help rebuild their marriage."

George Clooney was "so close" to his pet pig he didn't want to have children, according to Elizabeth Daily.
The star's ex-girlfriend believes his change of heart with regards to love and marriage - having recently got engaged to Amal Alamuddin - has come after he finally got over the death of his swine Max.
Speaking to The Sun on Sunday newspaper, she said: "He didn't need children, Max was his baby. He loved that pig like nothing else. It was the size of a table, absolutely huge.
"I would just be hanging out round George's with giant pig chilling out beside us. It had its own special pen and at night it would sleep on the floor right besides George's bed. It got in that bed at times.
"They were so close it was like father and son. When Max died in 2006 he was really torn up. Maybe now there's no Max he'll start to feel the pangs of parenthood. That would be great for him."
The 'Monuments Men' star was also hurt by his divorce from Talia Balsam, with Elizabeth admitting she was delighted he was getting over his refusal to marry again.
She added: "He didn't want a child to get as hurt as the husband and wife had been by a divorce. George was devastated by his divorce ... He didn't cry about it to me or get upset, it was a very measured but firm decision - no to another marriage for him.
"I'm so shocked by also very happy and excited that he's ow found a woman worth going back on his word for - something George Clooney doesn't do much of.
"It really shows just how terribly in love he must be. It's great."

One Direction are filming a follow-up to their movie 'This Is Us'.
The superstar boy band are currently on their 'Where We Are' world tour, and it has been confirmed they are being recorded for a sequel.
Director Morgan Spurlock told the Daily Star Sunday newspaper: "Yes, there will be a follow-up to 'This Is Us'.
"At this moment Ben Winston is with the band on their world tour filming what happens. He worked with me and is a great producer."
The first movie missed out on the Oscar for Best Song, and Morgan has revealed Simon Cowell would love them to be given a prize this time round.
He added: "I know Simon Cowell wants the band to get awards for this and was upset when they missed out on being nominated in the music category for an Oscar on our film.
"It was a good song and I was surprised that they weren't even considered. This time he will want them to try again."
Meanwhile, The Who singer Roger Daltrey has admitted he "admires" the 'Story of My Life' hitmakers, joking he would like them more if he was a teenage girl.
Speaking to the Sunday Mirror newspaper: "I admire what they achieved.
"If I was a 16-year-old girl I would love them, but I'm not. They're nice guys."