My family was lucky enough to get our hands on a wii fit. If you have a wii, buy the wii fit. It checks your BMI, weight and gives you an estimated age, I am 36 and my wii age is 46 Yikes. My 10 year old and I set it up last night and both did 30 minutes on it. What a work out. It has a yoga, aerobic, strength training, and balance work out components. It is worth the money.
Also, put a chair behind you, and then slowly lower your body into a squat and barely brush the chair with your rear end, then slowly bring yourself back up. It works!