The Power Within is a 1995 karate film.
Stan then gets up and asks the top jocks girlfriend out. The top jock becomes furious and tries to punch Stan, but Stan grabs his fist in defence. A fight breaks out, and Stan ends up defeatingjocks in the process. Soon Stan meets up with an evil man named Vonn, and also meets a monkey that is actually a reincarnated version of the old man. Stan discovers his powers were in him the whole time and defeats Vonn, gets the girl and is happy.
Source: Wikipedia