Knowing when to stop cannot be the same as giving up: one is strategic, the other is defeat. You may stop now to continue when better prepared; or you may need to retreat today to be able to fight again tomorrow. Your survival will sometimes depend on such choices. The strategy should reflect the circumstances in which you find yourself and your enterprise. But giving up or quitting says that you have lost control over those circumstances and you are neither capable nor willing to go at the task again. . . Yes, sometimes you will have to abandon an idea for the sake of a better one, be honest with yourself when this happens. Do not conflate giving up with knowing when to stop.