I am in no way minimizing any physical issues, as I have numerous and similar issues myself, but I thoroughly enjoy competing in USPSA matches.
Yes young(er) galloping gazelles slaughter me when much movement is demanded (although I have a growing reputation as "Hey, ain't you the guy who shoots 'em if you sees 'em?"), but it gives my shooting purpose.
Visit here www.USPSA.org
for local events.
Beats just standing around.....