Good Will Hunting

Will Hunting has a genius-level IQ but chooses to work as a janitor at MIT. When he solves a difficult graduate-level math problem, his talents are discovered by Professor Gerald Lambeau, who decides to help the misguided youth reach his potential. When Will is arrested for attacking a police officer, Professor Lambeau makes a deal to get leniency for him if he will get treatment from therapist Sean Maguire.
Some people can never believe in themselves, until someone believes in them.