I’m not just a columnist; I’m also a career and life coach. I have a radio show, and I am a regular contributor to CNBC. To make my schedule even more hectic, I also interview celebrities and authors for Borders books.

I work a lot. I have very little free time, and I have less and less time for myself. So, last month, when I heard I had to interview some doctor about some book—it felt like just another job, another interview, just something I had to prepare for. But interviewing Dr. John Ratey for Borders changed my life. I didn’t see it coming. I wasn’t looking for it to change my life. It just happened. Dr. Ratey had just released his new book called Spark: The Revolutionary New Science of Exercise and the Brain. In the book, Dr. Ratey discusses a high school in Naperville, Ill., where they approach physical education a little differently. The students don’t simply play dodgeball and soccer. They wear heart monitors and are graded on the amount of time they are able to keep their heart rate in the optimal aerobic range for their body type. After PE, the kids attend classes like normal.

As a result of their targeted physical education, the standardized test scores of the entire student body have jumped. In math, the school placed sixth in the world. On the science section, Naperville shocked everyone when they outscored every other school—in the world.

The statistics blew me away. And Dr. Ratey’s explanation of how exercise impacts your brain is amazing. Dr. Ratey has proven that when you exercise, it changes the physical structure of your brain! It increases your speed of processing, your memory. In a nutshell, science has proven that exercise primes your brain for success and makes you smarter.

But that’s not the truly amazing part. I mean let’s get serious. What about me? Not to sound crass, but I’m running a media company, not taking math and science exams (thank goodness). How can I use this secret weapon in my everyday life?

Dr. Ratey informed me that if you want to think clearer, beat stress, put the damper on your depression and boost your confidence, you only have to do one thing: exercise. He turned my entire world inside out. I had always thought of exercise as something I had to or was supposed to do. I did it simply to keep my butt smaller than it’s genetically predisposed to be. My source of motivation was vanity.

Dr. Ratey’s research gave me new motivation to go for a run. Now, for the first time, I am able to see exercise for what it truly is—a way of getting what I want, a way of priming my brain for success, a secret weapon. Now, when I’m stuck and can’t figure something out, I go for a jog, clear my head, come back and—bam—I figure it out! Dr. Ratey’s science at work! If I have an important meeting and I want my thinking to be at its sharpest, I make sure to exercise beforehand.

I know you’re busy. You’re stressed-out. There just isn’t time. I felt exactly the same way. I was just talking to a guy about his book, but, suddenly, I was handed a secret weapon. And consequently, my mind is sharper, I feel motivated and less stressed, and I have more energy. As a result, I’m healthier and so is my business.

Mel Robbins is a nationally syndicated radio talk show host, CNBC contributor, spokesperson for Microsoft and serial entrepreneur.

Read Mel's weekly SUCCESS blog.