best exercise for someone with arthritis

I walk and do an arthritis water aerobics class.

I do the elliptical for 45min at least 3 days a week

I'm 31 and have had Rheumatoid arthritis since I was 12, so I've tried it all. Swimming is great if you are mobile enough to shower and change. Leslie Sansone's " walk away the pounds" videos are low impact, physiotherapist friendly yet a great cardio work out. Squats, lunges and free weights ( around wrists for sore hands) are great when you can do them. Squats using a stability ball behind your back on a wall can create intensity and joint support. For the harder times,when flares are imminent, I've learned not to push myself into flares by over doing. There are hundreds of chair exercise videos which can keep you fit in the worst of pain. I just had a total hip replacement and need both knees done yet I continue an exercise regime based on simple physiotherapy plus " flexy ladies chair yoga for sever arthritis" and HasFits " chair exercises for seniors" All of these videos are free online. My motto: modify if needed, push, but not to severe pain and always keep moving even if it's inch by inch!

I have arthritis in my knees, i do a lot of aerobic exercises, initially i had to take pain killers before and after a session but as your body gets use to exercise your bones strengthen and knees became less painful. You do have to keep it up though, if i miss sessions then i stiffen up and joints become painfull again.
Water aerobis and swimming is excellent as well.
Good luck in what you do.