You can get more done by doing less.

This, says real estate investor, trainer, and infomercial pioneer Dean Graziosi, is one of the biggest secrets to success and happiness. I spoke to him recently about life, work, and the need to eliminate tasks that waste our time. More on that later. First, let me tell you a little about Dean.

He was born and raised in a town called Marlboro in upstate New York. Life wasn’t easy. Dean’s parents divorced and remarried over and over, and he moved more than 20 times by the age of 19. His first business was chopping and selling firewood. Then he bought wrecked cars, fixed them up, and sold them. Then he bought a rundown house, fixed it up, and rented it out. And he did all of that before he was 20, without a college education.

Dean reminds me a lot of myself. My first business was selling illegal fireworks to kids at school when I was 8 years old. Then I started a pool-cleaning business that made a $250,000 per year. Then I launched a business on Wall Street and made a bunch of money there. Now I’ve got Spartan. I didn’t start or run any of those businesses the traditional way, where you go to school and learn about the industry and then work your way up someone else’s corporate ladder until you eventually go out on your own.

So Dean and I are kindred spirits when it comes to business. Perseverance plus trial and error has worked for us both.

You may know Dean through his infomercials. He started in 1999 with a course on making money with cars, eventually switching his focus to making money with real estate. He’s been on TV every day ever since. Over the years, he not only found financial success, but he created new ways to promote on television.

“I was the first one to buy time and do a live interview on TV,” Dean says. “A couple of times during the interview, I would hold up my real estate book and tell people they could buy it. I sold a million copies of that book through that infomercial.”

Dean’s latest project, Millionaire Success Habits, is not about real estate or cars; it’s about success in general. And that’s what I wanted to talk about when I met him. Initially we talked about knowing your True North: what it is that drives you to do what you do. Dean and I (and pretty much every other successful entrepreneur) agree that successful people always know where they’re going and why they’re doing what they do. They know their True North, and they set their GPS to get them there.

I’m well aware, however, that even when I know where I’m going, I tend to run into all sorts of obstacles, roadblocks, and other setbacks. This is as true with my business as it is with ultrarunning and obstacle course racing. The trick for me is knowing which barriers I need to deal with, and which barriers I need to avoid or otherwise ignore.

I like the way Dean puts it. “Everybody has a to-do list,” he says, “but we’re all scraping for time, which is why we need to make a not-to-do list.”

He suggests that as you go through your week, make a list of everything you do during your day. Then, at the end of the week, look at your list and find the stuff you don’t need to be doing. Then you can make a note next to the things you should quit, the things you should automate, and the things you should delegate. When you do this, space opens up, and you have time for stuff that can go toward your purpose and your vision.

Dean says that when he creates a not-to-do list, he generally looks at return on investment. “Even if I have to pay somebody $100 an hour, if I can make more than that by focusing on something else, then I get a return on the investment by outsourcing it.”

I couldn’t agree more. I have to ask myself: “Do I really need to be changing light bulbs and cleaning toilets and sweeping the floors of my work space?” No, I do not. My business is much better off when I’m focused on more important responsibilities, so I delegate the tasks that might sidetrack me and I focus on the bigger picture of reaching my True North.

This is a great way to look at decisions related to business as well as life in general. Higher-level business functions are things for me to deal with, along with my family and my health. Dry cleaning and grocery shopping and the mundane (but still important) aspects of running my business can almost always be delegated. And plenty of other things can be crossed off my list entirely. If something doesn’t make my life or my business better, then I don’t focus on it at all.

That said, I can tell you from experience that the hardest word to say in the entire English language is no. People ask me all the time to do things, help out with things, lend my name and expertise to their projects, and I always want to say yes.

But before I do, I step back and look at my life and my business and ask myself, “Do I see a lot of value in doing this, and do I have time to do this fully and completely?” If I can’t answer yes to both questions, then I say no, even when I feel bad about my response.

I find that every successful person can effectively say no, even if they don’t have a formal no-to-do list. They just innately know that they need to eliminate unnecessary distractions and impediments, to automate necessary but time-consuming repetitive tasks, and to outsource or delegate when they’re better off spending their time and energy elsewhere.

It’s a different way of thinking, but it inevitably clears the path for success.

Subscribe to Spartan Up! to hear interviews with high achievers every week.

The opinions expressed here by Inc.com columnists are their own, not those of Inc.com.