Why on earth ride your bike for 24 hours? Good question seeing as I'm about to do it.
"The best moments in our lives, are not the passive, receptive, relaxing times - although such experiences can also be enjoyable, if we have worked hard to attain them. The best moments usually occur when a person's body or mind is stretched to its limits in a voluntary effort to accomplish something difficult and worthwhile. Optimal experience is something that we make happen. Such experiences are not necessarily pleasant at the time they occur, yet these could have been the best moments of life. Getting control is never easy and sometimes it can be definitely painful. But in the long run optimal experiences add up to a sense of mastery - or perhaps better, a sense of participation in determining the content of life - that comes as close to what is usually meant by happiness as anything else we can conceivably imagine."
- Mihaly Csikszentmihalyi