Shawshank Redemption is a story of a man [Andy Dufrain] who seems to be at peace in a place so overwhelming that others got 'institutionalized' [one convict when freed committed suicide because he couldn't adapt to life outside prison. Another convict said "every time I have to go take a piss I can't squeeze two drops without first asking my manager" - this was when he started to work at a supermarket].
Andy never looses hope, while he himself suffers he chooses to struggle in ways big and small. He helps a kid [who doesn't believe in himself and so ends up returning to prison time after time] pass an exam; he writes a letter a week over a long period to get funds for the prison library. [When he finally gets the funds and a response asking him to stop sending the letters, he starts sending two letters a week!]. While he does all this he digs night upon night for a long time with a tiny hammer to get through - to get his freedom.
It shows he was not institutionalized. No, he was a believer.
[Interestingly this is in contrast to the prison warden who keeps the bible with himself and professes to be a man of God!]
The hero it seems does well monetarily too. Andy makes money for the warden [through various projects] and manipulates to successfully get the money once out of prison. While he does this he also sends incriminating evidence to the police owing to which they come after the warden [and I imagine the prisoners also get their salvation from his tyranny]
A beautiful part of the movie is where Dufrain locks the guard and puts a beautiful operatic piece on the mike and so it plays throughout the prison. A person said: "I have no idea to this day what those two Italian ladies were singing about. Truth is, I don't want to know. Some things are best left unsaid. I'd like to think they were singing about something so beautiful, it can't be expressed in words, and makes your heart ache because of it. I tell you, those voices soared higher and farther than anybody in a gray place dares to dream. It was like some beautiful bird flapped into our drab little cage and made those walls dissolve away, and for the briefest of moments, every last man in Shawshank felt free."
When asked why he did this Andy says [when he is taken out of a two week solitary confinement where he was sent as a punishment for this]: "that music - it's in your heart now, no body can take it away from you".