Smoking is probably the worst thing you can do to your heart. No level of smoking is safe, and the risk of chest pains and heart attack rises with every cigarette smoked daily. Base your diet on fruits, vegetables, whole grains, and nonfat or low-fat diary products. Consume no more than 300 milligrams of cholesterol daily. Eat a small amount of walnuts or other nuts at least a few times a week.
Physical fitness is associated with a low risk of heart disease.
For heart benefits, a minimum program would be 30 minutes of brisk walking daily. More is definitely better. But if you are sedentary and over 50, get medical advice before beginning an exercise program. Keep your weight at a healthy level. Being overweight is bad for anybody's health, and the percentage of obese people in the U.S. and Canada is rising.