Well I'm fairly thin by build so it's a decent fit. Severe Arthritis runs in my family and so far I've managed to keep my mobility when other people in the family couldn't move their joints anymore so I'd say I'm ahead of the game.
Primarily yoga. I got my start from Hittleman's 28 day program and continued from there rotating a set of routines one per each day.
I supplement this with an evening walk of about 45 minutes.