I began riding because of the need for transportation. Almost immediately, however, I was riding for the sheer pleasure of the physical sensations of pedaling a tricycle (and, eventually, a bicycle).
Riding because I enjoy how it feels has stuck with me, and I hope it never goes away. The fitness angle is a terrific bonus, of course. I'm probably in better shape now than I ever was at any time in my life.
Competition? Not yet. So far I'd much rather ride for pleasure and my own satisfaction than to try to out-ride a lot of other people. Besides that, I'm not sure I have the competitive streak necessary.
I've been on fund-raising rides, too, although not many. And bicycle tours! I'll have to put those on my bucket list, and hope that when I can retire I'll still be able to do plenty of riding!