Running in inclement weather can sometimes be a struggle. Support from a running group can help you finish.
Never run from stray dogs. Unless you want a little adrenaline rush. A dog nipping at your heels is a sure way to PR.
Watch out for the wildlife when running on nature trails. It is not uncommon for deer, fox, or other such animals to jump out, or even worse, for a skunk to make its presence known. And for those running in grass, snakes may be underfoot.
Running in the sweltering heat of summer can be particularly dangerous and can seem to make your blood boil. Be sure to stay hydrated. (Just in case you don't get the joke (if it really is one, this is the river of boiling blood- my students LOVE this Canto in Inferno.)
For races with thousands of runners, it can sometimes take an eternity to cross the start. Be patient.
Watch out for those who might crash at the finish line of a long distance race. You don’t want to trip over them. No need to hurt your ankle.
Near the end of your race, it may seem as if your legs might fall off. No matter what happens, get to the finish line; crawl if you have to. You trained too hard to not finish for any reason.