Training tears you up. Literally. When you go to the gym to work out any muscle, your muscle breaks down and get these microfiber tears. These tears allow the body to rebuild itself slightly bigger and stronger. The important thing about the whole process is the time to heal. The healing process rebuilds the muscles so that it CAN get stronger. It's said that your muscles takes 24-48 hours to fully recover and become stronger, but do long distance runners have that luxury?
Advanced long distance runners do not have the luxury to take a day off every other day in order to maximize the rebuilding of their muscles. A simple explanation is to call to mind the race we are train for. For example, a marathon consists of 26.2 miles, but according to most training menus for advanced runners, their longest runs would be 22 miles. Why is that? It's because those runners run almost every day, accumulates all the mileage from the previous days (like a roll-over) and though the muscle has some time to recover during each night, on their day of rest, the body has enough time to heal and rebuild itself from the accumulated damage done to the muscles.
All the pain that comes in the training isn't something that I look forward to, but I know that the pain that I am going through shows that I am indeed becoming stronger, faster. It shows me that every cramp I get, the soreness in my legs, they're all worth it because I'm becoming the runner that I want to be. As I write this, I am in pain from working out my calves, and hiking three miles in the morning. If I had been in shape, I wouldn't have gotten into this whole mess, but because of the shape that I want to be in, the individual I want to be, I'm going to go out and go for a run, because I have a goal in mind that no pain can ever wash away. This pain will be something that I will use to become stronger, reminding me to not lose focus towards my goal. This pain is not where I stop, but where I keep on going, filled with perseverance and determination.
(After writing what was said above, I ran 7.04 miles in 51:42, a 7:21 min/mile average listening to"We Won't Give Up" by The Afters)