I have a low back injury and would like to start an exercise program. What is a safe program to do?

A lot! Lifestyle changes are important like not smoking, weight control with regular exercise. You can use medication if no contraindications, try a back support, & activity modification. If no better, then see your doctor for further evaluation and treatment. Exercise can include walking, elliptical and stairmaster machines to start and then increase it along with gentle stretching and core strength.