I was recently asked what is the one exercise that really and truly everyone should do at least once a week. I didn't even have to think about it..S Q U A T S! Not only do they strengthen your legs and bum but they do so much more. They allow you to be mobile into your old age. Allow less stress on your knees and improve your balance. Yes all other exercises are awesome but there is a reason why some form of a squat is in every type of exercise (yoga, pilates, ballet, aerobics, karate,etc!)
Thought I would get you started on less falls in your old age..20 a week may just keep the hip replacement away!
http://www.youtube.com/watch?v=t6ZE3O6svwc