Motivation

everyone tells me how motivated I am for running marathon. "wow you did a marathon and you're how old? You're so motivated." But honestly it was one of the most challenging things to be motivated for, because in all honestly who is dying to run a marathon for usually more than 3 hours?  You would think running a marathon would give me unlimited motivation and great self esteem but not really. I felt good about it for a while like wow, I did I ran my first marathon, this is so great- but I'm in school.I had really had big exceptions for myself, I had good training since I started my plan in August, I wanted to qualify for Boston but that did not happen, so was per usual, I was crushed- I ran my first marathon at 21 years old while starting a new school, and was upset? Why?  I want to do great things in my life and for some reason, even when I do great things, I don't give myself credit for it. I have to believe myself when I say: I did a run marathon, and that is something great. I did something most people don't have the chance or motivation to do in their life and that is freaking awesome.