Skip the fried and fatty foods, and try to get at least half an hour of exercise every day. Eating right and keeping active are the gifts that keep on giving.
If you set up these habits now, the benefits will last a lifetime. And if you plan on having children someday, it's a good idea to take a multivitamin that gives you plenty of folic acid -- between 400 and 800 micrograms a day. Start taking folic acid at least 1 month before you plan to get pregnant, and keep it up during your first trimester.