Here are some good places to start:
You don't need a gym membership to benefit from exercise. The American Cancer Society recommends that survivors get at least 30 minutes of moderate activity five or more days a week. What you do is up to you (and your doctor), but the main point is to get your heart rate up. Exercise can also improve mood and sleep, reduce stress, control weight gain, boost self-esteem, and protect against other killers, especially heart disease and diabetes.
Don't smoke, and eat and drink mindfully
You can still get this disease if you don't smoke or drink and you eat a low-fat diet. But some studies draw a link between breast cancer and the same poor lifestyle habits that encourage heart disease and diabetes. Research has shown that being overweight or obese (especially if you're past menopause) increases your risk of breast cancer, especially if you put on the weight as an adult.
Get regular checkups
Set up a schedule of regular visits to your doctor. Each year without a recurrence marks an important drop in your risk, and five years out is a big milestone. Still, recurrences can occur 20 or even 25 years after a first bout with breast cancer, so experts say you'll need to continue screenings.