If you feel bad at 10 miles, ...

If you feel bad at 10 miles, you\'re in trouble. If you feel bad at 20 miles, you\'re normal. If you don\'t feel bad at 26 miles, you\'re abnormal.
If you feel bad at 10 miles, you're in trouble. If you feel bad at 20 miles, you're normal. If you don't feel bad at 26 miles, you're abnormal.
 Robert de Castella

More phrases

Don't settle in the land of barely enough. That is where you are, it is not who you are. That's your location, it's not your identity. No matter what it looks like, have an abundant mentality.
The by-product is that they more people you help, the "richer" you become, mentally, emotionally, spiritually, and definitely financially.
 T. Harv Eker
Happiness doesn't depend on any external conditions, it is governed by our mental attitude.
The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is.
To improve is to change; to be perfect is to change often.

Quotes from the same author

The marathon's about being in contention over the last 10K. That's when it's about what you have in your core. You have run all the strength, all the superficial fitness out of yourself, and it really comes down to what's left inside you. To be able to draw deep and pull something out of yourself is one of the most tremendous things about the marathon.
 Robert de Castella
When I was about 14 or 15, and running in a pretty muddy cross country race, one of my shoes stuck in the mud and came off. Boy, was I wild. To think that I had trained hard for this race and didn't do up my shoelace tightly enough! I really got aggressive with myself, and I found myself starting to pass a lot of runners. As it turned out, I improved something like twenty places in that one race. But I never did get my shoe back.
 Robert de Castella