Tips from marathoner Brandon Seils such as “Get High”, “Pain is your friend” and “Break through the wall“:

For most runners, there’s a wall at the three mile mark. This goes for the most beginner runners up to and probably including the long-time marathoners. The first three miles of any run are the most difficult and painful to get through. After this point, however, it’s easy to “just keep going.” Back when I was training for the Boston Marathon, and would go out for 2+ hours on a 20 mile run, the hardest miles were the first three. It’s also these first three miles that make it difficult for running to become habit. You really have to struggle past this, in order to develop a tolerance for the sport.