There are lots of quotes that I find inspirational, motivational, or generally useful in some way. But I'm not sure that I can come up with one off the cuff tha

There are lots of quotes that I find inspirational, motivational, or generally useful in some way. But I'm not sure that I can come up with one off the cuff that "permanently changed the way I think." But this one probably comes about as close to meeting that bar as anything I can think of. Absorb what is useful, discard what is useless and add what is specifically your own. -- Bruce Lee