You learn that there are different stages of “tired”. First comes a regular tired, when your heart rate is going up and you want to stop and catch your breath and rest. If you push through that, you enter a comfortable pace and a stage where it feels like you can go forever.
Then your muscles become tired. They complain about every incline. After that your mind starts to go. You can’t remember why you decided to run this far. You wonder why you chose this specific course. You tell yourself that you might not be able to make it. That you’ll fail.
If you push through that, it gets better. Your muscles don’t feel as tired anymore. They’re a little tight, but there’s no pain. Your mind starts to clear and you are only concentrating on one thing: BREATHE. So you just breathe. And push on."