When it comes to inspiring entrepreneurs and business owners, Richard Branson is at the top of most lists.

After all, he's a billionaire who has started over 400 companies and is easily in the running for the busiest individual in the world while still enjoying life.

Entrepreneurs striving to make their impact in the world look at Branson from the surface and may be tempted to think that he has some ultra-secret to credit for his success.

However, if you're looking for a productivity hack, a morning routine, or the one book to read to change it all, you'll be disappointed.

The secret to Richard Branson's success and productivity is summed up in two words: "Work out."

Simple as that. He claims that exercise is his tool that helps him double his daily productivity. Working out is often expressed as a great way to enhance your physical appearance. But working out is, more importantly, a tool that provides a huge ROI toward your productivity and overall well-being.

If you're on the fence about investing fully into the power of exercise, here are three reasons why you should start today.

1. Improving brain power.

When you're building a business and striving for massive amounts of career success, optimizing your brain output is an essential tool to making that desire a reality.

When you exercise, you're going to be mentally sharper, which leads to better decision making throughout the day. This equates to delivering better presentations, better food choices, and better choices within your daily operations.

When you work out, you're increasing the amount of oxygen flowing into your brain while releasing various other chemicals that help improve your memory and concentration.

2. Make more money.

When you get off your bottom, you increase your bottom line. There's a correlation that benefits both men and women when it comes to prioritizing the gym and making more money.

According to associate professor Vasilios Kostas of Cleveland State, of those who head to the gym at least three times per week, men made 7 percent more while women made 12 percent more than those who don't.

The underrated reasoning for this increase is a boost in self-confidence. Often times, we're our own worst enemy with the things we say and think about ourselves. Working out helps reframe the perception that we have of ourselves along with the energy we radiate out into the day-to-day world.

3. Reduce stress.

Waiting in line at Starbucks, delayed trains, traffic, deadlines, proposals, friends, family, and many other things can all be a form of stress.

None of these scenarios are likely to vanish from your life. However, you can prepare yourself to handle them better through working out.

Working out provides an outlet for releasing any pent-up tension from the day. The Anxiety and Depression Association of America reported that seven out of 10 of adults in the U.S. deal with daily stress or anxiety.

When you work out, you're releasing endorphins and building up yourself to respond and be resilient to upcoming stressors. Don't overcomplicate it when it comes to exercising-- even a 20-minute walk can provide a much-needed jolt of happiness.