Heck, at 37, by all rights, you're still a young pup!
I am fortunate enough to live in San Diego, which by the way, has the BEST weather, all year around, of any place in the continental U.S. And that also means we have OUTDOOR sporting activities 12 months out of the year, including a non-stop parade of triathalons, duathalons, 10Ks, 5Ks, you name it, we have it, unending. ( I personally don't participate in any of them 'cause "long distance" ANYTHING bores the hell out of me--the very reason I love PK--a LOT of fun in a small space & time.) Observing participants who engage in these activities in my neck of the woods includes ALL age categories--forget 40-somethings--we're talking 70+somethings in damn good shape. One thing that those guys (and gals) have in common is that they have PACED themselves those 7 decades to still be able to enjoy those activities.
In sharp contrast, I have a very close personal friend who will be turning 80 next month. He is/was a natural-born athlete, high school and college baseball star, drafted by the St. Louis Cardinals, went into engineering instead, but continued his athletic endeavours in his personal life. In the mid-60's, he was probably one of the first to take up "recreational" running, based on a ground-breaking book that came out at that time, the "bible" for training astronauts, called "AEROBICS"--a term we are all NOW familiar with. If you weren't alive (and aware) in the mid-60's, NOBODY was running the streets for "fun". You were a freak if you did. The only people running were high school or college athletes training for track or cross-country, or some other athletic endeavour. He bought the very FIRST "running shoe" (by a new company called Adidas) that was specifically designed for street running, and by todays standards, prehistoric in design, with almost no real cushioning in the sole of the shoe for miles spent pounding asphalt and concrete. After about 15 years of averaging 5 miles/day with very few missed days and not running with a very smooth-flowing gait (he would land HARD on his heels), he had to hang up his shoes after suffering from shin-splints, knee problems, hip problems, you name it.
But it didn't stop there. He simply transferred his activities to the tennis courts for the next 15 years or so, where he diligently continued to degrade the situation--just at a slower pace. His rewards--shoulder replacements, hip replacements, spinal degeneration--a complete structural breakdown, where he now moves about like a man who is 120, instead of participating in a 5K's with the rest of the 80-somethings, which he could have easily done had he PACED HIMSELF!!!
I hate to beat a dead horse, but at 37, you potentially have a long and useful athletic future ahead of you as long as you keep it all in perspective. Find the things in PK that "fit" you--DON'T go trying on someone else's moves just because they look cool, but will probably ending up breaking YOUR neck. To each his own. Stay within your comfort range, and if you are going to attempt something OUT of that range, do it in such small increments that it won't be such a big deal to accomplish. Think "gradualism"--it works.
As a P.S. I receive Jesse's WOD--and cringe. Because of a lingering wrist injury, I am completely unable to even attempt half of the exercises he suggests, and certainly the numbers of reps are completely out of the question. But what I do is to take each WOD, find the exercises I can do, ramp the reps WAY down so that I can make an honest attempt at the numbers of SETS he is shooting for. The foundational philosophy that the WOD is based on (Crossfit) is revolutionary. I just have to make it work for me within my limitations.
Go and sin no more.
