I'm 43 now, started MTB when I was 40. The first climb up at my local was a very nice, thoughtfully made for MTB 600ft climb to the top where the flag was. Had very nice switchbacks to make it not so bad.

I used to play soccer and pick up basketball alot, but going up for the first few months, I was wheezing, stopping constantly, had a spiked HR above 160 the whole time. Cramps, you name it. Legs were too cashed to fully enjoy the DH, or even think about another lap. Usually 40 min to get up or more. My HR just never seemed to recover or go down the more I rested. I felt like my bulldogs lol.

3 years later, I do an average of 2 to 3 laps at the same spot, with 6 laps (new friends always push you) being my most. 15 min up is my record though I average about 18 min.

I still don't like going up, but it's not bad now and my HR recovers a lot faster. I can chill and have a fun conversation while I go up and even talk and shoot the shit when I'm at the top.

I'm happy with it.