It's been over 2 years since my doctor suggested taking up exercise to deal with depression, and it worked. I almost always get enough sleep (I can tell when I don't, I turn into SuperBitch), eat a pretty balanced diet, and exercise regularly. I am, as my doctor says, "living the good life." I can tell when I'm not doing enough to keep myself balanced. Yoga helps a lot.
I never ever ever want to go back to being overweight and unhealthy. Ever. I WAS miserable. Now I'm not.