"Doubt can only be removed by action."
Think about this when you are half way through the run of an Ironman or Half-Ironman race and you are feeling blue. Your mouth is all gummy and one more gel would make you throw up. The smell of gatorade is nauseating. You're leaning against the wall as other racers start passing you more frequently. And they're all talking to you, "Come on..almost there." The head is dizzy. Just putting one foot in front of the other is like asking yourself to climb Mount Everest. You doubt you can finish. You just want to stop, fall down and lay on the side of the road. End it right there.
So, Think about those words. Take action. And finish that damn race. All Doubt will be removed.