As I wrote in a letter to a loved one recently, a sign posted very visibly in the workout room of my local 24-hour gym (by the treadmills) gives the famous Winston Churchill quote "Never, never, never give up". It is intended to be a motivational tool for the members as they work hard to get in shape. I'm on board with it, too, but with one caveat...
Yes, determination usually pays off with our goals. Keep trying and eventually there should be a positive payoff. It helps, also, to be focused on one's goals with specific outcomes in mind, to be completed according to a timetable, however loosely that is devised. Time should be allotted as well, giving a regular period when priority is given to working on the goals in question. Good and well, I say. But...
Sometimes, as goals are pursued, it becomes increasingly apparent that they really aren't the ones worth pursuing, and they change. This changing of goals to things more worthwhile isn't a violation of Churchill's exortation, though: it is a sign of maturity, not an indication of "giving" up, but rather "growing" up...