I feel that a long run gives you the opportunity to show what kind of person you are. Or at least to try and become the person you want to be.
The long run
For me that's someone who doesn't give up. Someone who shows willpower. Someone who is strong and keeps on going when the going gets tough.
By going for a long run, I know that I'll become that person. Because going for a long run requires me to show all these characteristics.
In the long run.