I'm your age and throughly enjoy the trails. Sounds to me like you've been out of it a while and sort of "got in over your head" on a challenging and steep trail. I don't think you're "too old", I dont think I am anyway. You just ride where you're comfortable and accept you'll fall occassionally. Just have fun and dont try to ride a brainless, invincible, 20-something's ride.
Too old? Heck when I'm on my mtn bike I'm a kid again!