For sure, walking, running, jogging, bike riding is pretty cool because you actually go somewhere & you can keep motivated by exploring places new to you. Any sport will help (how poker got on ESPN is odd) swimming is a great activity & saves you from the pounding on your feet & knees. Cross x skiing, tennis, soccer you name it, it will all work
Leg lifts. Lie on your back on the floor. Keep your legs together and straight and lift your feet approximately 2 feet off the floor. Hold that position. Separate your legs for about five seconds. Bring legs together again and lower them. (Up, Apart, Together, Down) Repeat this as much as you can. It works great for the tummy muscles too.