During a battle for his life, the soldier did not notice the cuts he received from the rocks, but when you fell while rollerblading and received similar injuries, you felt significant pain. This is best explained by:

Adrenaline

Explanation:

During the war a soldier had his adrenaline going and when your adrenaline is going you don't feel pain until after the fact. But when you fell you had no adrenaline going.

Adrenaline

Explanation:

A soldier in battle is afraid for his life and in a scary event so adrenaline is released to stop the function of things that are unimportant to the situation so you can protect yourself. After the soldier is out of battle it is likely that he would have pain from the injuries. Like if you were trapped under a car your body isn't going to focus on digesting something you ate earlier. If you fall and get hurt while rollerblading and that is it your body is still able to focus on other functions.