Ashton Kutcher lost 12 pounds training for a marathon

Kutcher spoke to Entertainment Tonight, saying he's lost about 12 pounds while prepping for the race, which is set for Nov. 6.

"The biggest change physically has been the transfer of muscle mass from upper body to lower body," he said, adding, "My wife [Mila Kunis] has been super supportive."

As for why he's doing the race, Kutcher said, "My baseline 'why' comes down to leaving life better than what it was given to me. My daily motivator is my kids and family."

He's been leaning on those close to him while preparing for the marathon. "Surrounding myself with a support system makes hard things much easier. Setting a pace that you can sustain is not the same thing as working as hard as you can," Kutcher said.

He will also be raising money and awareness for Thorn, a group that builds technology to defend children from online sexual abuse.

"The marathon itself is an elevating opportunity for the work that we have been doing for over a decade with Thorn," he said. "A chance to show the folks that have been working so hard to make our vision reality, that I'm in it with them and willing to go to the last mile."

"Every move we make is in consideration of creating scalable outcomes that help children have lives where they can just be kids," Kutcher added.

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