Have to agree with Cheryl, do what feels good.
Most days I do treadmill or elliptical, some days I'll do recumbent bicycle. When I can, I do light weights - I try to do SOME weights a few times a week, but then, I started exercise and weights when I was in my 30's. (more than 20 years ago)
Yoga can be wonderful, and Tai Chi is oh so fabulous. I have trouble finding classes at the times I can take them.
Basically - stay as active as you can, don't push yourself to exhaustion or pain. Do be sure you clear with your doctor if you're starting an exercise program.
Actually, I feel better on days I've exercised - it gives me more energy and I typically have lower pain levels.
~"I find hope in the darkest of days, and focus in the brightest. I do not judge the universe." (Dalai Lama)