When you push too little, you don't grow that much, or at all. When you are performing below your level, you aren't exactly hurting yourself, but you aren't moving forward. When you push too hard, you are performing higher than your level, hurting yourself in the process, but damaging yourself and aren't able to move forward until you heal. In order to maximize the forward procession, it's important to go at a pace where your body is recovering fast as you're hurting it.
When I was running the 12 hour race, I needed to be able to go faster than everyone to win. However, if I had run as fast as I could at the beginning of the race, my body would have not been able to keep up and I would have hurt myself and not able to continue for the 12 hours. Had I walked for 12 hours, I would not have been able to compete and complete a high number of miles. In order to compete, I needed to run at a pace that I would be able to work with for the whole 12 hours. Will it hurt to run the 12 hours? Yes. Will I be able to do well with a pace that I could keep? Yes.
No matter what you do, whether it be running a race or working on a project of some sort. Work hard enough that it hurts, but not too much that you won't be able to recover from it.
Today's training consisted of doing my 15 pull ups, 40 push ups, and cycling for 30 minutes (followed by a 15 minute sauna). Because of yesterday's running and exercise, I kept my exercising to a minimum so that I would be able to work on my stamina while not chiseling away at my growth. To reach my goal, I need to balance my training in order to grow as efficiently as possible and not hurt myself to where I would need to stop for a while. What I would like to do is to get to a point where I won't have anymore peaks because I'll have a firm foundation, consistently growing, rather than moving in bursts.