1. Even if it is only 50 degrees, don't wear a long-sleeved cotton shirt on a run. You may think that you will be fine, but after one uphill mile it will be all sweaty and you'll be hot. Then, later, you'll be freezing in the damp cotton.
2. Drinking water is good. Drinking water the day before a long, difficult run is even better. If you fail to do this you will have a splitting headache and you'll want to die. Also, you should buy a damn hand-held water bottle and use it already.
3. Just when you are about to die of dehydration, a knight in shining armor on a white horse (or, a husband in shiny spandex on a single speed mountain bike) will show up and offer you a drink from his bottle and words of encouragement. Fairy tales do come true!
4. Do not eat chips and hummus and halloween candy for dinner. There is no nutritional value in that and your body needs decent food to work properly. Your body hates you right now.
5. While trail running in late fall, sometimes you have to shuffle sideways down a rocky descent, holding onto a tree for dear life. It's the only way to avoid a rolled ankle. Also, you should buy some damn trail running shoes already.
All excuses aside, today's run was probably my worst ever. But shit happens. Bad runs happen. I'm sure even elite athletes have bad days. What matters is that I did what I could and I'll try again another day.