How to break the shy barrier?

How can i break the mental barrier of physical training?

• okay here is the problem. I don't play cricket but i attend the physical training with the cricketers because the teacher who trains them told me since i wanna go into the army i should come training to keep my body fit, plus he gives me extra stuff to do (to get my body ready for the army toughness) so I'm like one of the tough guys in training. But my major weak spot is my running but not in the physiological sense i think it is more a psychological thing. Could anyone help with any sort of ideas on how to break that mental barrier it's like when I'm running i tell my body i could do all the laps but then on the second one or half-way through the first one my mind just completely rebels against my body and i automatically stop running...i finish the laps though but not running sometimes i have to walk some and that's not satisfying enough for me i really need to crush that mental bloc please help me Thanks a lot :)

• Answer:

  just keep pushing yourself keep running no matter what your body tells you i hate running but once i was in a basketball game, and about half way through i got so tired. i wanted to be taken out but the coach never took me out. (he happened to be my dad). i kept started jogging instead of running for about 45 seconds. and that was enough of a break (i broke the whole mental barrier thing). and after that i could run faster then ever for the rest of the game. you just gotta force yourself right when you feel like you'll die. it worked for me. try it next practice(: