This article originally appeared in Fast Company.

We all know what being burned out feels like, and most of us understand that burnout comes from overworking ourselves. How often do have thoughts such as, “I’m behind, No matter how much I do, it’s never enough, or I’m running out of time…?” But what you probably haven’t done is actually ask yourself, “Why do I overwork myself?” The answer is usually not an easy one.

However, motivation is fueled by both nonrenewable and renewable sources. Renewable fuels create sustainable energy, whereas nonrenewable fuels lead to burnout. Without realizing it, many of us plug into the nonrenewable fuel of fear as a motivator. The fear of competition, of failing, of time running out, of lack, of disappointment. The fear of not being smart enough, good enough, creative enough, powerful enough, worthy enough, talented enough.

Plugging into fear as a motivator may work in the short term, but it will burn you out. You’ll find yourself in a vigilant state constantly scanning for the next problem to solve, the next goal to hit, the next thing to prove yourself. Your focus is on what’s missing. When such a state becomes familiar, you may find it difficult and uncomfortable to relax.