I don't know if the original poster is still reading, but here's my advice, part of which I heard somewhere:

1) Find ways of making exercise a fun part of your routine.
2) "Eat food. Not too much, mostly plants."

By getting exercise through things that you find exciting or interesting, it's more likely to be something you'll stick with. Exercise must be a permanent part of life to stay in shape. It doesn't have to be the same activities all the time; I seem to cycle my interests every few months, and the weight stays off.

I heard 2) from the radio, I think. "Food" means things mde from ingredients your grandma might have had in h Er kitchen.