"Never give up" is a statement that has been ingrained in all of us since we were young. But what if you aren't really succeeding? What if the only thing that's keeping you going is the thought of how much time and money you've already invested? Should you still persist?

A Huffington Post feature says that what you're worried about is called "sunk cost." It's time, money, and effort that you've given or used up in the past, and certainly not something you should be basing your decisions on, economists say. After all, why base your future on something that has already been spent and lost?

Dr. Richard Nisbett, a psychologist from the University of Michigan, tested the concept of sunk cost on college professors, surveying them about whether or not they'd be willing to give up on a failing research which they have been working on for a long time. Results show that those who chose to continue due to their past investments were less successful than those who were willing to start all over.

This just shows that although persistence is admirable, you must also know when to quit.

Sunk cost also applies to all aspects of life. You could be staying in a job you don't like or in a relationship simply because you're considering the amount of time and effort you've spent making things work. But that shouldn't be the case--knowing when to say enough is enough may be the solution. If you're feeling unhappy about where you are now, try taking stock of things. Maybe it's time you move on.

(Photo by Paul De Los Reyes via Flickr Creative Commons)