I think the biggest challenge, apart from recovering from serious injuries, is powering through more vaguely defined but occasionally nagging issues that hold me back. So here are some of those issues and how I try to deal with them.
Sleep: We all get that insomniac monkey on our backs at times. It can become exponential; the more we stress and try to sleep, the less able we are to do so. Often, as in the night before I had my appendix out, we can't sleep due to physical discomfort or pain, so I guess the trick is to weed out those potential causes first. Once I have it down to nothing obvious, or peripheral stress (which can be the worst), I try to blank out my mind entirely. No thoughts, no images, no counted sheep... and that works better than anything else I've devised to this point.
General Fatigue: Tied to (lack of) sleep in many instances, this one simply needs to be ignored first; if it persists, I take a breather. I make fatigue my friend (boy, that sounds odd) in the sense that my body is sending me a message that I have to interpret. Is it sleep, or nutrition, or overwork? All of the above or something else entirely? There's an answer out there somewhere.
Fatigued or hurting Muscles: A lot more detailed analysis needs to go into these issues to ensure that injuries don't become aggravated, obviously. However, I believe very strongly from personal experience and from watching and listening to others that people can mollycoddle their aches and pains entirely unnecessarily. People need to fight through these pains with a lot more fortitude than they often do. Just look at the ordeals that ultra distance runners go through to appreciate what can be endured. I think that once a person internalizes this approach to pain and hurt, they are well on their way to successfully completing long distances and other endurance activities. Sounds pretty self-evident, but we've all seen and heard the whiny little excuses and we've all been sorely tempted to succumb to them ourselves. Toughen up, and as you know the reward is that little bit of a swagger that you can allow yourself for having done so...
So that's your diatribe for the day.