Imagine trying to knock down a brick wall by pounding your head against it. Literally. You finally realize that it's not exactly the smartest idea in the world. So you quit.
What?! You quit? But quitters never win, and winners never quit, right? They (the infamous They) have been telling you that for you whole life! So it must be right, right?
WRONG! Winners quit all right... but they know when and why to quit. There is a time for everything, including ceasing to put your energy into unproductive and downright futile efforts. Then you can put that energy into something more productive, or at least fun.
(Mind you, there's also a time for sticking it out, and slogging through the tough times. Conventional wisdom isn't always wrong!)
In the specific case of knocking down a wall, after you bandage your wounds and get some painkillers, and maybe an X-ray, you can go get a sledge hammer, or a crane with a wrecking ball. (Or hire someone to do it for you. You don't have to do everything yourself.) Or you might decide you really didn't need to knock that wall down after all, and go watch a movie or read a book or play a game or whatever you do for fun. Maybe some tennis practice... against that brick wall.
Back to the real world, though, there are all sorts of situations you can apply this to. Your job. Keeping up with the Joneses. This month's governmental "War on a Vague Concept". Whatever. Leave a comment below, to tell us (me and the other readers, assuming there are any) what brick wall you've been banging your head against... and what you intend to do instead, now that you know it's okay to quit.