Entrepreneurship is an emotional rollercoaster unlike any other sport: The highs are so high, and the lows are very low.

This week, a recently exited employee asked for a larger severance package because of the hard times ahead for his family. I worried about a different team member facing a mental health crisis, whom I desperately wanted to help. But I had to respect his privacy and couldn't do much more than introduce him to some resources. We faced a potential inventory shortage that could derail our growth projections, but we also earned two new investors. The list goes on... amazing highs and difficult lows.

Nurturing your health is a critical business investment

I began my first business at 22 years old. Since then, I've started or co-founded five businesses--all of which are still operating today. 

In my twenties, it seemed I could pull from an endless wellspring of energy. As I got older, the problems got bigger, the days seemed longer, and I learned my energy is a finite resource.  

I had all but lost touch with exercise, good sleep hygiene, or sound nutrition--and every other healthy habit. I spent every ounce of energy focused on business-growth activities and didn't make time to re-invest in the most important asset: my health.  

Then, after losing a loved one, I had a 180-degree change in my thinking: If you don't have your health, you truly have nothing. 

Thankfully I rediscovered exercise--and eventually nutrition and mindfulness--and learned the most important entrepreneurial lesson to date: Optimal health is rarely discussed as part of a business strategy, but absolutely should be, for three primary reasons: 

1) Exercise leads to better decision-making

At the end of the day, the role of a founder, and most other senior leaders, is decision-making. And in a startup, there is a relentless onslaught of questions, challenges, and opportunities coming your way. 

Many of those can be quite emotional. This is a high-stakes, zero-sum game. People's livelihoods are at stake. If you can't manage your emotions, you can't make good decisions. 

The pillars of lifestyle medicine all contribute to maintaining emotional equanimity and better decision-making: sleep, community, stress-management, exercise, and optimal nutrition. Investing time in those areas seems like a luxury, but in fact they should be a core part of your day. 

In particular, exercise is a secret weapon for better decision-making. 

This has been clinically proven: One study put it quite simply: "Sedentary behavior is associated with impaired cognition, whereas exercise can acutely improve cognition." Other studies show that regular exercise causes certain brain regions to actually grow, improving memory and thinking skills. 

There is no shortage of studies suggesting that exercise can enhance concentration, lengthen attention span, and improve overall executive function. 

Want to make your team better? It's not about more hours in the office; it's about more hours at the gym, on a trail, or in a yoga studio. 

And it's easy to prove for yourself. 

Next time you're facing a thorny question, just go for a walk, preferably outdoors. You'll see the effect in just a few minutes and probably have an answer before you get back. 

2) More energy increases productivity 

More than a decade ago, I was lucky to discover Tony Schwartz's work at The Energy Project. I was quickly convinced by the simple idea that we shouldn't be managing our time; we should be managing our energy. 

This intuitively makes sense: We all go through cycles of high and low energy, so planning our days around those ebbs and flows is an easy "work smarter" tactic, albeit far from the norm in most offices.  

At our company, we try to do calls in the afternoons, inspired by Paul Graham's "Maker / Manager Schedule" concept. Mornings, for most people in my experience, is the time of peak creative output. 

For me personally, my clearest thinking happens before the sunrise. By early afternoon, it's hard for me to put together a presentation or write an advertisement script. So that's when I schedule my regular check-in calls or admin work. 

How's all this related to health? 

You probably already guessed it: When you're healthy, and you feel awesome, you have more energy and sustain higher energy levels for a longer period.  

In the 24/7/365 game of business, more energy means more opportunity to make an impact. 

3) Stamina: It's a marathon, not a sprint

An entrepreneur friend once told me that, waking up an hour earlier, or staying awake an hour later, is like earning an extra 15 days per year. (Because you're getting 365 extra hours to work that year.) 

This is the seductive "just work more" thinking that leads people to confuse hours worked with results accomplished. It's not about getting 15 more days at your desk; it's about getting to the finish line. And winning. 

And anyone who has done it will tell you not all energy is created equal. 

There is a difference between fueling with clean-burning whole foods, lots of water, good sleep, community involvement, and consistent exercise, as compared to three espresso shots and the adrenaline that comes from not sleeping before a big presentation. 

Both can get you through a day, but only one can get you to a finish line that's years away. 

Building a business is a marathon, not a sprint. Nurturing the asset, by investing in your health, is the only way to finish strong.