ego
Not even Chris Pratt knows the truth.
Learning to let go of your ego is very easy in theory, however can be very difficult to execute in the moment. When I think about times that I've been frustrated I always recognize a single thought that resonates in my head, "Drop your ego! You have nothing to lose here, but a whole life to win."
Ego is sometimes characterized as the "false self." Some spiritual teachers advocate destroying the ego. I do not. If we love it, it can grow up and be helpful.