Much like Felix, I avoid snackage.
Also, I run like three to four miles a day for stress relief purposes. Apparently it helps keep you healthy, too!
Oh yeah, and I avoid high fructose corn syrup like the plague. I am convinced that it is the devil. As soon as I almost completely cut food containing high fructose corn syrup out of my diet, simultaneously with not using my car and walking/taking public transit everywhere, I literally lost about 15 pounds, my acne cleared up, and my hair started growing in healthier. After the initial "getting over it" phase, I also just stopped ever wanting it. I still take care of my teeth the same as ever, and my dentist has remarked on how much improved they are.
I am convinced that high fructose corn syrup is spelling doom for all humanity.