As a young man my first mentor was cigar chomping salty SFC Young.as I was trying to explain away some failure of some sort I said "but I worked so hard!" His reply was " A jeep stuck in the mud works hard it just doesn't go anywhere. It's not how hard you work it's how right you work." SFC Young was a great influence in my life. Much of what he taught a headstrong young man stays with me to this day. His expectations of me were in proportion to his opinion of my abilities and he never let up until you met them. He steered me through my development as a solider and to ultimately a 37yr military career.
So IMHO what makes quotes so great are the people behind them that took the time to teach inspire and most importantly live the lesson in the quote. In our politically correct society these people have become rare. Certainly our loss.