The definition of insanity, it's been said, is continuing to do the same thing over and over again and expecting different results. In the case of the Jets and Tim Tebow, things are clearly getting a little insane.

After zany coach Rex Ryan repeatedly passed over underthrowing Tebow for the underperforming Mark Sanchez and underwhelming Greg McElroy, ESPN reported that sources said Tebow refused to play in the team's Wildcat formations. In an exhausting game of “he-says-he-says,” Tebow claims that's nonsense. Some say Ryan quit on Tebow. Some say Tebow quit on the Jets.

The mere suggestion that Tebow might have quit got the would-be QB riled. He said that while he doesn't mind criticism about his performance, being called a quitter impugns "your character, your integrity, who you are as a man." (Read the The 7 Life Rules Tebow Follows.)

Letting go can be particularly tough for guys, experts confirm. "Men are often socialized to play with pain and play to the end, even if they end up destroyed in the process," says William Pollack, Ph.D., a psychologist and associate clinical professor at Harvard Medical School who specializes on men's issues. "That’s because they feel as if their masculinity is at stake, and if they quit they'll be less of a man. They have to realize that the stronger man knows when to stop."

All of which made us wonder, whether in a marriage, a job, or a game of football: When is it actually the sane choice to face the facts, admit things aren’t working, and yeah, quit?

Heidi Grant Halvorson, Ph.D., is an expert in the area of motivational psychology who focuses on helping people succeed at their goals. (Click here for Halvorson's 13 Tips to Reach Your Fitness Goals.)

She says there are times, however, when it makes sense to give up -- if you're doing it for the right reasons. We should not quit, she says, if we think we won't succeed; persistence and hard work are more important than ability. (Tebow could actually learn to throw.)

Halvorson, however, cites three good reasons to abandon a goal:

*Lack of time. If you're already working two jobs and caring for a sick parent, say, you might as well put that dream of mastering professional badminton on hold.
*If the goal is costing you too much. You probably can complete a marathon, but if the pains in your feet during training turn out to be stress fractures, stop.
*When your goals compete. You want to put in 90-hour weeks so you can rule that law firm, but you also want to see your children grow up. Something has to give.

Is your New Year's resolution to get in shape? Try a leg-searing, heart-pounding plan from the star himself.
Click here for The Tim Tebow Workout.

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