It would be hard for most people to imagine what could possibly have been missing from Tom Bloch's life back in 1995. He had a great job as a CEO and a seven-figure salary to match. He had a wife and two sons. And that CEO job? Well, he took over the family business from his father, who, 40 years earlier, tweaked the spelling of the family name so people would pronounce it correctly. Then he did their taxes, under the name H&R Block.

But despite how great his life might have looked on paper, Bloch wasn't happy. His wife worried he wouldn't make it to 50. So Bloch left it all behind to become a math teacher in inner-city Kansas City. In 2000, he opened University Academy, a tuition-free charter school. His new book, "Stand for the Best," describes what he learned from the experience. He shares what aspiring business owners can learn from it as well.

Entrepreneur.com: A lot of entrepreneurs wrestle with the idea of giving up established careers to strike out on their own. Having dealt with this in your own experience, what advice would you give them?

Tom Bloch: Someone once said, "Someday your whole life will flash before your eyes. Make sure it's worth watching." I began to think about that quote and I realized we all have one life and we've got to make sure we use it in such a way that it's a happy life and a useful life. I read somewhere that about half of all people don't really like their jobs. And I thought, "What a waste of a life that is to get up every morning and do something that you really don't like." I felt something was missing from my life, even as a CEO making plenty of money, so I began to figure out what my real passion is and I decided to follow my heart. There was less of a risk for me because I could walk away from a lucrative position to become a teacher and not have to sacrifice my lifestyle. But I know for many folks it's a risky proposition to think, "I've got a comfortable, secure position. I've got a steady income." And to give that up for something that's uncertain, that can be scary. I understand that. But there's always that risk in not doing it--that someday you may regret having not followed your heart. I feel like it's never too late to make that decision. But it does take courage. It does involve risk. But I do think it's important to do your homework first before making a significant life change.

Entrepreneur.com: You say in your book that it's never too late for someone to find his or her calling. How does this relate to an entrepreneur looking to start a business?

Bloch: So many people take advantage of their life experiences. There's almost an advantage in some respects to waiting until mid-life to make a significant career change because often times, the experience you had in your previous career can be utilized and can benefit the next chapter in one's life. There's plenty of examples out there. My wife thought I was going through a mid-life crisis and that's why I was thinking about making a big change, but I really feel it was deeper than that, more fundamental. I know people much older than me who have made significant career changes and they actually worked out quite well. I would just encourage people to not settle for anything less than what they really want out of life because you might be able to achieve it.

Entrepreneur.com: University Academy seems to have a strong element of social entrepreneurship. Talk about how you apply the double bottom line in your new career.

Bloch: The guy I started University Academy with said, "Who has the nerve to start an inner-city school? It's not a growing business. It's a business that's been in crisis for decades. Why would anybody in their right mind do that?" But the rewards can be so tremendous by doing something where the benefits are beyond one's self. That's what I found to be really the greatest reward as a teacher--to connect with students, to make a difference in their lives and to find out years later that the impact was significant in a positive way. We've had five graduating classes now, and all but two students have gone on to college. I often wonder how many of those kids would've graduated from high school. How many would've ever gone to college? It's really a great reward. At the end of my first year of teaching, one of my students gave me a little ceramic apple that said "Greatest Teacher" on it. I took it home to my wife and told her, "I got my bonus today." She looked at me as if I were crazy. I explained to her that this little gift from a student meant more to me than some of those bonus checks I got at H&R Block that had several zeroes on them.

Entrepreneur.com: How did your previous business success allow you to be better equipped to deal with an industry that was struggling?

Bloch: One of the problems with education--and particularly urban education--is that folks don't always understand that it is a business. It is absolutely a service business, and it can be successful. There are plenty of examples of really successful inner-city schools in this country. But it's important to realize that it is a business. In any service business, the key ingredient above all is people. To have good people is essential. Using some principles that are commonplace in business, for example, performance pay is considered sort of a dirty term in the education business. A lot of folks think it's a bad idea. But teachers and administrators should be rewarded for outstanding performance and certainly good teachers and administrators should have the opportunity to make more money. It certainly motivates people in the business world. Why shouldn't it motivate people in the business of education? Some of those basic business principles that are applicable to education are often discarded because folks have a very idealistic view of public education in this country. I consider myself an idealist. But there's no question that I was able to take advantage of so much of what I learned in my previous career that applied perfectly to the education setting. That's probably true for many people who are changing careers or starting a business. They can take advantage of those prior experiences and apply those principles in their new businesses.

Entrepreneur.com: Your book talks about the importance of urban education to the overall health of the country. How does urban business tie in to this concept?

Bloch: The kids who are in our schools today, whether it's suburban schools, urban schools or even rural schools, these are the folks who will be leading this country and leading the businesses. About 93 percent of the kids in our school come from families who qualify for the free and reduced school lunch program. My goal is to see many of these kids not just get a job, but become really productive entrepreneurs. Ideally, they will create companies in the urban core that will provide tens if not hundreds of jobs for other people. That's one of the greatest accomplishments any entrepreneur can make, which is to create jobs for others. We're just starting to see some of our very first students graduate from college, and I heard about one who's working for Google. You feel a sense of pride to know that this is a young man who could go on and achieve great success not just for himself, but for the community in which he lives. Many of our kids--I get such a kick out of it--they are budding entrepreneurs. They'd love to start their own businesses.

Entrepreneur.com: Any final thoughts for aspiring entrepreneurs?

Bloch: It's so important to figure out not only what you're good at, but what you really enjoy doing, and not to be afraid to launch something that's different and may involve some risk. If you don't do it, you may always regret not having taken that step. It's been 13 years since I made the change in my life, and I had a lot of people second-guessing my choice. I had some people think I was really nuts to give up what I gave up. But for me it was the right thing to do. Sometimes we have to not listen to what others say. Sometimes we have to go against what is common sense. We live in a very work-oriented culture, and sometimes we might want to pursue things that don't necessarily make sense from a career-building point of view, but which will bring us greater satisfaction down the road.