This guy did a race, a tough race. And he could have had given plenty of excuses not to do it or not to even sign up for it. I am sure it was difficult. My able bodied friends who have done it complained about it. I cannot even imagine what this guy felt. Yet he did it.
So today, throw out all of your excuses and your fears. Go do the thing that you have been putting off. It does not matter how big or small the thing is. It is all relative to the size of your battle and your circumstances.