There are hundreds of different exercise routines that do not involve any kind of special equipment at all. By use a simple stretch cord (you can use a bungie cord), a weight (you could use a heavy book), and a good YouTube video or DVD the sky is the limit. My wife is currently doing Hip Hop Abs (DVD), maybe a little faster pace for someone with joint replacements, but the idea is the same. She uses absolutely NO equipment. It's all body weight against itself resistance. By the way, she's lost 20 pounds in the last 2 months!