While genetics certainly plays a role, never, ever, let age be an excuse. Plenty of people either start, or continue to be active, well into their later years. Heck there's a pro mountain biker who consistently places top 5 nearing 40.
And if you can't be active, there a tons of sedentary hobbies, too. Life is a series of experiences, enjoy them while, and whenever, you can.
I started downhill and enduro mountain biking when I was 40. 2 years later I'm pretty decent at it. I take some pretty large jumps and drops and go down crazy steep technical shit. You're never to old to learn. Just make sure you wear the protective gear for the sport and you'll do fine. Also you'll feel amazing when you conquer an obstacle that used to give you trouble.
While genetics certainly plays a role, never, ever, let age be an excuse. Plenty of people either start, or continue to be active, well into their later years.
Hubert Schwarz famously cycled around the world... twice. IIRC, the first time at 40 and then again at 46. Previously, at age 35, he completed all of the - then five - world's Ironman competitions in a single year.