If you’ve never run regularly, start by walking and inserting 15- to 30-second jogging intervals every five minutes. As you become more fit, run for longer stretches and decrease the time between intervals. If running is too much for you, stepping is the next best thing. Although walking fast up stairs is great, going down can strain your knees…so go slow. Or eliminate knee stress by stepping up on an exercise step-bench and then stepping down backward. Face the bench as you step up and down, periodically switching the leg that leads. Add arm movements to up the intensity. (If you don’t have a step-bench, use the bottom step of a staircase.) Walk, run or step at least 30 minutes daily.