The 9-to-5 grind has created a cult of workaholics.

Unfortunately, the 8-hour workday hasn't budged in 100 years. Nevermind that the Information Age represents the biggest shift since the Industrial Revolution and that family structures have changed dramatically since the early 1900s.

Workers still get in their cars every morning and clog up the freeways and do it again at night.

Mondays are dreaded. Wednesdays are "hump days." Friday mornings bring relief because they're the final push before the weekend.

The idea that workers are expected to endure 70% of their week so they can enjoy the other 30% is collective insanity.

Why my company moved to a five-hour workday

My company decided to do things differently. I run a business that sells stand-up paddleboards, so a shorter workday that freed our employees' afternoons for extraordinary living was a natural fit for our beach lifestyle brand.

We decided to move to a five-hour workday, where everyone works from 8 a.m. to 1 p.m. By eliminating an hour-long lunch, we only reduced our work time by two hours. Our employees don't get paid less, and I still expect them to be twice as productive as the average worker.

The results have been astounding. Last year, we were named the fastest-growing private company in San Diego. This year, our 9-person team will generate $9 million in revenue.

When I tell people my team only works five hours a day, their response is always, "That's nice, but it won't work for me." The 9-to-5 is so ingrained in their minds that they can't imagine anything else.

But you can reduce your hours by 30% and maintain the same level of productivity. Here's why:

Humans are not machines. Just because you're at your desk for eight hours doesn't mean you're being productive. Even the best employees probably only accomplish two to three hours of actual work. The five-hour day is about managing human energy more efficiently by working in bursts over a shorter period.

Happiness boosts productivity. Studies show that happier workers are more productive, and it makes sense: Having time to pursue your passions, nurture your relationships, and stay active gives you more energy emotionally and physically.

Fewer hours create scarcity. In their book, "Scarcity: Why Having Too Little Means So Much," Sendhil Mullainathan and Eldar Shafir write that having less time creates periods of heightened productivity called "focus dividends." A five-hour workday offers baked-in time management by forcing you to prioritize high-value activities.

How to implement a five-hour workday

The question I hear most often from people is: "Can a five-hour day work for everyone?"

Unfortunately, if your job looks the same as it did during the Industrial Revolution, the answer is probably not. Professions that require a 24-hour presence, such as law enforcement, emergency response, and nursing are not good candidates for the five-hour workday. Nor are jobs that require working in unison with a large number of people (such as film production).

But for the vast majority of knowledge workers, clocking fewer hours that generate higher productivity is very manageable. Here's how to get started:

1. Apply the 80-20 rule

Tim Ferriss's "The 4-Hour Workweek" is required reading for anyone looking to adopt a shorter workday. One of the most important ideas discussed is the Pareto Principle: 80% of production comes from 20% of efforts. Evaluate your workday to identify those 20% activities and eliminate the rest.

2. Shift to a production mindset

People who dismiss the five-hour workday outright usually think it's impossible because they measure work in hours rather than output. However, most knowledge workers aren't paid by the hour. They're paid a flat salary.

To help my team shift to a production mindset, I rolled out a profit-sharing plan where 5% of profits are doled out to employees who demonstrate exemplary productivity.

3. Nix the "always available" attitude

One of my biggest objections to moving to a five-hour workday was reducing our customer service department's hours. I worried that if we cut our open hours in half, we'd lose half our business.

But I realized that we didn't run a convenience store. Our customers bought new paddleboards maybe once every five years. It didn't matter when we were open as long as our customers knew our hours.

So we made the switch, and nothing fell apart. We still get roughly the same number of calls each day, and emails are usually answered within hours.

Understand that even in our instant-gratification society, being available all day isn't necessary. You just need to communicate when you are available.

4. Use technology to boost efficiency

One of the unexpected benefits of the five-hour workday is that it exposed weaknesses in our company that had been hidden by man-hours. To allow our warehouse and customer service employees to work 30% less (without growing our staff), we had to figure out how to serve the same number of customers in less time.

The obvious solution was leveraging automation. In the warehouse, we reduced our packing and shipping time using software. In customer service, we overhauled our frequently asked questions page and created video tutorials to help customers help themselves.

Once you put a time constraint on work, it forces you to consider how you can get technology to do the heavy lifting to increase your output. Make use of email auto responders, set up automatic trigger-based tasks, and learn to use keyboard macros.

5. Don't restrict yourself to a 25-hour week

My employees know they can always walk out of the office guilt-free, but top performers still put in the occasional 12-hour day.

Just as with a 9-to-5 job, recognize that there will be times when you want or need to work an extra-long day. But when you can leave the office at 1 p.m. to go surfing or pick your kids up from school, work isn't separate from life; it's all just living.

Moving my staff to a five-hour workday was one of the hardest decisions I've ever made, but today my employees are happier, more productive, and invested in the business.

You can make the leap to a five-hour workday, too. You just have to shift to a production mindset and let go of the fear. You'll be amazed by the productivity and freedom you can achieve when you stop mindlessly punching the clock.

Stephan Aarstol is the author of "The Five-Hour Workday: Live Differently, Unlock Productivity, and Find Happiness." He is CEO and founder of Tower, a holistic beach-lifestyle company, which includes Tower Paddle Boards, Tower Magazine, SunglassesByTower.com, and a direct-to-consumer surf-and beach-lifestyle company at TowerMade.com. For more information, please visit www.fivehourworkday.com and www.towerpaddleboards.com. Connect with Stephan on Twitter @stephanaarstol.