Exercising just three times per week can help you lose weight. Put aside 15- 20 minutes if you are just starting out. Try to increase your workout to 45 to 60 minutes per workout. By exercising at low to moderate intensity you will burn less calories than high intensity such as sprinting. You can torch calories quicker by increasing your level of intensity. If you are just starting out take it slow. You will see progress if you are consistent.