If you can find exercise that's "play" for you, that's the trick.

I like hacky sack and kettlebells. I can play hacky sack for 15 minutes, wherever I am, and easily keep my heart rate between 160 and 190 bpm. I can do kettlebells in my bedroom in 15 minutes, and stay pretty strong and capable. They're both genuinely fun for me, and leave me feeling better (lower stress, more alert, stronger, more agile, more attractive, less like a lazy slob).

I never could spend 10 minutes to and from the gym, and another 45 there, or anything like that. I feel lucky to have found these things I do like.