|Older === more time to recover, to do new tricks (but less to understand how to do them), and much more 'endurance' to practice,... as my father always told me, and now I begin to feel it, even if I have 20 a 2nd time....
5/6 hours sessions (Rsk8 or windsurf) are not a problem now, but were hard when I was 20 (same weight). Think endurance and knowledge improved.... But 2 hours after a good session I'm quite sleepy.... a good night and 2 resting (or working) days are good for me to fill up the batteries (muscles and brain). It's not easy to find the good life cycle length and not overcharge your body.