Hey Alex! I just decided to have my mid-life crisis around Christmas time, 2010...took up kick-boxing in Jan 2011 and parkour in June 2011, the month I turned 45! Never too old to start. Ironically, if you had certain job categories..oh, like a member of the Armed Forces, Firefighter, Search & Rescue, nobody would bat an eye at a person your age taking up a sport that involved running obstacle courses! Not only would they not bat an eye, they would expect you to be physically fit enough already to do something like that! So, keep on moving!
The only thing that slows me down at my age is my job considerations. I have to consider what type of work I'll be doing in the days after parkour class. Some days, I can't be replaced if I injure my hands at class (concrete is unforgiving). At those times, I'll skip class until the following week. Otherwise, well, I'm insured and live in a country with universal health care.(It's good to be Canadian)!!