I've known people who thought that reaching their potential would come from shoring up their weaknesses. But do you know what happens when you spend all your time working on your weaknesses and never developing your strengths? If you work really hard, you might claw your way all the way to mediocrity! But you'll never get beyond it.
Working on a weakness within a strength zone will always produce positive results. Working on a weakness outside of the strength zone will not.