I am a member of our local IMBA club and enjoy helping on trail days. Keeps my firefighting tools busy in the off-season too
I have to admit that I do not do enough of it.
I wish I had more time to building new trails on my own place. It was easier when the boy was at home so we could work together on it. Also wish I had a little more vertical drop to work with but I'm not complaining too much.