I have a family history of heart problems...how can I prevent this for me?

My family has had a history of heart problems and diabetes. I'm 15, 6'0'', and around 200 lbs. (My weight changes a little bit every day) Both my dad and grandpa have had heart problems, and I really don't want that to hit me, or any other generation after me. (thats probably impossible to prevent though) How can I reduce my chances?....I AM an athlete. I practice the art of Tien Shan Pai Kung Fu. I workout everyday except friday. I have a good diet. I hardly ever eat junk food or drink pop/soda.....sooo.......???