If you want something you've never had do something you've never done

Last year I got a poster from a teacher of mine. I had wanted it all year long and finally on report card day at the end of the year, he gave it to me.The poster said, "If you want something you've never had, do something you've never done." At the time I wasn't sure what it meant but I knew it meant something true.
I figure that this phrase means, that if there is something out there that you really want, then you may have...