I have a character I play intermittently in my Japan-themed RPG environment -- a Buddhist nun, tiny and blind and lame since birth, who memorized the Buddhist canon by hearing it read aloud to her.  She lives in self-imposed austerity, although her father (who does have money) insists on providing her with servants -- who live as she does, austerely -- so that she doesn't starve to death.  (She's willing to make a few such concessions -- after all, it's hard to spread the dharma when you're dead.)

At one point I had her say one of the usual Buddhist vows: "Though sentient beings are numberless I vow to save them all."  Another player who was new to the game -- and probably didn't know about Buddhism in detail -- said something like "Whoa, is she nuts?!"  I laughed, but at the same time I was actually kind of touched by that outburst -- there was just something charmingly naive about it, something that cried out to be spoken to.  So I explained as best I could.

A person who takes that vow [I said] doesn't expect to fulfill it literally.  It's a mind-expanding gesture, a way to take the limitations of your life and explode them from the inside.  You've probably seen the Adidas "Impossible Is Nothing" ad campaign at one point or another.  I took a shine to it the first time I saw it: it was a clever pop-culture packaging of hope and aspiration.  (One of the early iterations of the ad, since turned into a poster, showed Muhammad Ali in his famous "Get up and fight!" moment.)

If you do away with rational limits of what's possible or impossible, even if only in a provisional way, you aim that much higher by default.  The hardest thing in the world is to do away with those kinds of self-imposed boundaries, to look beyond them and see something else, both for yourself and the benefit of the world around you.