The MC is the person who do all the heroics right?
Who saves everybody and defeats the villain in the end.
Ask yourself this, Why?
Why would your nobody character or better yet your powerful character give up their pretty good live simply to make the lives of others simpler?
Why would they time and time again put their lives in danger for people they don’t know?
Every character needs a reason to do all this. A reason that is probably focused on themselves.
Now please remember for them self could mean for someone they love and care for.
If you just realized your hero is one again too perfect and has no reason to be doing what he is doing then I can only say welcome to the writing world.
Sit down and write down your Character’s like’s and dislikes. Write down the people in his live and why they are so special to him. Write down a tragic moment of his past. Write down the enemies he has at the beginning of the story. Write a separate lists for the enemies he has during the middle and the end of the story. Write down if he feels he has to prove himself to someone. Write down who he will help during the story. Write down both the good and the negative impacts the events of the story will have on your character.
At the end of this you should have an idea of why your character does what he does. Just remember your character may do things but he doesn’t always have to be happy with.