If you don't, don't start.
Smoking is the single greatest cause of preventable illness in the country.
It is bad not only for smokers but for the people around them. Maintain a healthy weight. Excessive weight is linked to heart disease, high blood pressure, diabetes, back problems and a host of other ailments. If you need to lose weight, do so gradually. Inactivity puts you at risk for ailments ranging from heart disease to osteoporosis.