There's no such thing as a bad carbohydrate.
I know runners who have suffered a tick bite and ended up with Lyme disease. Ill take an angry moose any day.
Grizzly bears eat people without the benefit of music.
The key to running a good marathon is to not listen to anyone's advice the last week before the race. That's when people tend to do stupid things that disrupt all the input and training of the previous months.
Prior to the 1976 Olympics, I was a 5,000m runner.
Train at the same pace day after day, week after week, year after year, and that's the kind of running the body adapts to. But break out of that comfort zone with a little speedwork now and then, and the body will learn to deal with the new demands.