Not that I can think of. I guess in a way it replaced the gym but that wasn't really a choice. Whistler has these things called "fitness centers" which are essentially useless to the way I like to work out, so I stopped, biking replaced that but I would gladly go back to being a gym rat if I could find a set of dumbells over 100pnds and a real squat rack
...[grumble]damn cable machines[/grumble]
Of course I would still mountain bike.
very few finishers? that's because the early stages of any learning curve are the most rewarding. after some time progress at anything becomes smaller and smaller compared to the workload required to progress. i know so many athletes, as well as artists, scholars, businesspeople, etc. who spend the majority of their time striving for that next bit of performance, progress, whatever...in reality they're standing still, passing time, letting life slip by.
my point? drop your old habit or hobby and learn something new. it's what life's all about.
Thats why I love mountain biking. Versatility. If I find I just am not getting any stronger, my bike handling skills might be improving or I ride park/djing. So many options on a bike its hard to stagnate for long.