This is part four of a ten part series on the Habit Pyramid, a set of core habits that allow us to live purposefully in spite of modern challenges. The foundation is built upon strong habits for personal health. If you missed any of the first three articles, you can catch up on healthy habits for sleep, eating well, and the dangers of sitting.

High Intensity Interval Training (HIIT) sounds like something for astronauts.

But it’s designed for regular people just like me and you. (Astronauts can use it too.)

In a nutshell, HIIT workouts pack a lot of benefits in a short amount of time.

If you’re anything like me, you struggle to find time to exercise. Between work commitments, raising kids, and other projects, personal time is often the first place we cut. Even if we know better.

We’ve got to stop doing that. It’s the worst kind of short term thinking, and it harms us and those we love.

Why Exercise?

In Spark: The Revolutionary New Science of Exercise and the Brain, Dr. John Ratey proves how regular exercise can improve the way our brains work and help ward off depression and stress.

If exercise came in pill form, it would be plastered across the front page, hailed as the blockbuster drug of the century. – Dr. Ratey

That’s one heck of a one-two punch: more of the good stuff and less of the bad.

Exercise is the single most powerful tool you have to optimize your brain function.

In a recent USA Today interview, Ratey explained, “a fast-paced workout boosts the production of a protein called brain-derived neurotrophic factor. I call it Miracle-Gro for the brain, and physical activity is one of the best ways to release this brain-nourishing protein. A workout at the gym or a brisk walk also seems to build better connections between brain cells. Studies show that regular physical activity may increase the production of cells in the hippocampus, the region of the brain involved in learning and memory. The end result is a brain that’s better able to perform in school, at home or on the job.”

In today’s tough economy, why would we pass up an opportunity to naturally boost our performance?

Now, let’s talk about the other side of the coin.

According to Ratey, exercise is absolutely an antidepressant. “If everyone knew that exercise worked as well as Zoloft, I think we could put a real dent in the disease,” he says. Here’s how he explains it.

Antidepressants seem to work through a bottom-up chain of events, meaning the activity begins in the brain stem and ripples through the limbic system until it reaches the prefrontal cortex. This might explain why antidepressants relieve the physical effects first — we feel more energetic before we feel less sad.

With cognitive behavioral therapy and psychotherapy, we feel better about ourselves before we feel better physically. Therapy works from the prefrontal cortex down, to modify our thinking so we can challenge the learned helplessness and spring ourselves out of the hopeless spiral.

The beauty of exercise is that it attacks the problem from both directions at the same time.

Exercise gets us moving naturally, which stimulates the brain stem and gives us more energy, passion, interest, and motivation.

We feel more vigorous. From above, in the prefrontal cortex, exercise shifts our self- concept by adjusting all the chemicals including serotonin, dopamine, norepinephrine, BDNF, VEGF, and so on. And unlike many antidepressants, exercise doesn’t selectively influence anything — it adjusts the chemistry of the entire brain to restore normal signaling.

None of us want to talk about this, but with 1 in 10 Americans over the age of 12 taking prescriptions for depression, we should be. Women, in particular, are 2.5 times more likely to be taking medication. For those of us with a family history of depression, perhaps this preventive approach is even more appropriate.

Studies also show that at every level, from the microcellular to the psychological, exercise not only wards off the ill effects of chronic stress; it can also reverse them.

Again, Ratey explains:

Exercise combats stress, leaving our bodies and minds more resilient.

It’s well known that the way to build muscles is to break them down and let them rest. The same paradigm applies to nerve cells, which have built-in repair and recovery mechanisms activated by mild stress. The great thing about exercise is that it fires up the recovery process in our muscles and our neurons. It leaves our bodies and minds stronger and more resilient, better able to handle future challenges, to think on our feet and adapt more easily.

When you say you feel less stressed out after you go for a swim, or even a fast walk, you are.

How Much Exercise?

Like almost all of my other “discoveries,” I came upon this one by accident too. In August 2010, I ran my first half-marathon in San Diego. It was very painful. My legs and cardio were fine, but my hips and core locked up at mile nine. Walking and jogging, I finished, but I couldn’t walk comfortably for nearly a week. And this was after sticking very closely to my conventional training plan, logging well over 25 miles a week.

Just before I left, I’d started taking bootcamp classes with some friends. When I returned, I kept up those workouts three times per week and ran 1-2 times per week (never more than five miles). Two months later, I completed the Harbor Half with zero pain, running the entire way. It was pure joy, one of the best runs of my life.

As my schedule compressed (with more work and older teenagers), I realized that the only exercise I was getting was my thirty minutes (on Monday, Wednesday, and Friday) and lots of leisurely walks with the dog. It was enough. Over the last year, I’ve lost another 8 pounds and several inches, I’ve never been injured (aside from tripping over my dog in the dark), and I’m able to handle stressful situations without “melting down” like I once did.

It turns out that numerous recent studies verified what I’d experienced. In addition to Ratey’s Spark, NY Times columnist Gretchen Arnold compiled her years of research into The First 20 Minutes: Surprising Science Reveals How We Can Exercise Better, Train Smarter, Live Longer.

In a recent TIME interview, Arnold shared a summary of her findings and her biggest surprise: “how little physical activity can make a very profound difference physiologically.  That did surprise me. I used to run marathons and like a lot of people, I really did think you had to run [and] your exercise had be fairly strenuous for a long period of time to get meaningful benefits. The science is very clear that that is just not true.”

How much is enough?

According to Arnold, “at least 20 minutes a day makes a truly profound difference in your health and dramatically reduces the risk of a whole host of diseases, particularly diabetes, heart disease and dementia, as well as cancer.”

How to Exercise?

For me, the scheduled classes are essential to keeping the habit. Without them, I’d never have kept up with my workouts during stressful times – when I needed them most. The combination of encouragement, camaraderie, and accountability is enough to get me over the hurdle. (For more on this aspect, read this article on how to make yourself workout .)

If you think you might need similar support, sign up for classes.  Any additional investment will be well worth the consistency you gain.

To find one, you can look for “bootcamps,” high intensity interval training,” “cross-fit,” or even zumba in your area. Do pay attention to your body as you’re starting out since injury prevention is goal number one. If you’re sidelined with an injury, you can’t get any benefits at all. (If you live near Corpus Christi as I know many of my readers do, I highly recommend my trainer Adam Farrell of Pinnacle Performance and Fitness.)

If you’re not interested in classes, I know of two other resources.

While I was in the Philippines for three weeks, fellow conference attendee Joe Bauer kept us in shape with similar workouts. He offers virtual coaching and guided health-focused vacations throughout the world. (If you live in the Pacific Northwest, he offers in-person coaching too.) If you need an extra dose of motivation and inspiration, Joe’s the perfect coach for you.

For the DIY type, Adam recently shared a TED talk about designing your own 30 minute workout. Watch it carefully and take notes to craft your own workout.

Now, I’d love to hear from you in the comments. What helps you exercise consistently? What are your favorite types of workouts?