On the other hand, I noticed that some people simply NEVER give up. They have ferocious persistence and they never let go of their goals. These people are like the bulldog that refuses to release its teeth-hold on a bone. The harder you try to pull the bone out of his mouth, the harder the dog chomps down with a vice-like grip.

What's the difference between these two types of people? Psychologists say there is an answer.

An extremely important guideline for achieving fitness success is the concept that, "There is no failure; only feedback. You don't "fail", you only get results."

This is a foundational principle from the field of Neuro Linguistic Programming (NLP), and the first time I ever heard it was from peak performance expert Anthony Robbins back in the late 1980's. It's a principle that stuck with me ever since, because it's a very, very powerful shift in mindset.

A lot of people will second-guess themselves and they'll bail out and quit, just because what they try at first doesn't work. They consider it a permanent failure, but all they need is a little attitude change, a mindset change, or what we call a "reframe."

Instead of saying, "This is failure" they can say to themselves, "I produced a result" and "This is only temporary." This change in perspective is going to change the way that they feel and how they mentally process and explain the experience. It turns into a learning opportunity and valuable feedback for a course correction instead of a failure, and that drives continued action and forward movement.

It's all about your results and your interpretation of those resultsDr Martin Seligman, a professor of psychology at the University of Pennsylvania, did some incredible research on this subject and wrote about it in his book, Learned Optimism. Dr. Seligman noticed that the difference between people who give up and people who persist and never quit is what he referred to as "explanatory style." He said that explanatory style is the way we explain or interpret bad events or failures.

People who habitually give up have an explanatory style of permanence. For example, they hit a plateau in their progress and explain it by saying, "diets never work" or "I have bad genetics so I'll always be fat." These explanations imply permanence.

Other people hit the same plateaus and encounter the same challenges, but explain them differently. They say things such as, "I ate too many cheat meals this week," or "I haven't found the right diet for my body type yet." These explanations of the results imply being temporary.

People who see negative results as permanent failure are the ones who give up easily and often generalize their "failure" into other areas of their lives and even into their own sense of self. It's one thing to say, "I ate poorly this past week because I was traveling," (a belief about temporary behavior and environment), and to say, "I am a fat person because of my genetics" (a belief about identity with a sense of permanence). Remember, body fat is a temporary condition, not a person!People who see challenges and obstacles as temporary and as valuable learning experiences are the ones who never quit. If you learn from your experiences, not repeating what didn't work in the past, and if you choose to never quit, your success is inevitable.