I'm 58, and was involved with gojo-ryu karate for five years in the 70's. Also a little judo and aikido. I'd like to get back into karate, but some arthritis and the passage of time make me wonder if I can really do the punces and kicks of my youth. Other than something like tai chi, is there a "soft form" of karate that I could study that wouldn't be so hard on the joints?