Set off on a 50 mile group ride and dropped after 9 miles due to heat exhaustion.

My worst:

Mountain biking on the 5th of July last year, didn't eat breakfast, because breakfast makes me ill. Didn't occur to me until later that I hadn't eaten dinner the night before either since I had a few burgers for lunch.

I bonked BAD. So badly, in fact, that a guy who had broken his frame while we were together on the trail walked it back to his car 10 minutes before I rode out.

When I got back to the trailhead, another ride had just changed into hiking gear to come rescue me.

The only thing that kept me going was pure fear, a huge thunderstorm had picked up and about 4 trees went down across the trail while I was out.