The endurance athlete is the ultimate realist.
You've got to be a little bored to be doing really good training.
During long, slow distance training, you should think of yourself as a thoroughbred disguised as a plow horse. No need to give yourself away by running fast.
There's no satisfaction without a struggle first.
Happy people don't run a 3:47 mile.
Run your own race at an even pace. Consider the course, the temperature, the weather, and most importantly, your current level of fitness.