This post is part of our long-running “How to get rich” series. Click see all the posts.

There’s this tendency to believe we need a revolutionary idea in order to get rich. The fact is, most of the world’s millionaires (and billionaires) got rich off of industries we probably thumb our noses at: fertilizer companies, trailer parks, and lawncare franchises work just as well as founding the next Zynga, Twitter or Facebook.

A recent article in Forbes drove home this fact when they profiled the Top 3 richest people in Africa. All three of them made their cash off industrial businesses:

1) Aliko Dangote, $10.1 billion in market cap in his cement company Dangote Cement. Also mills flour and refines sugar.

2) Nicky Oppenheimer, $6.5 billion from selling his stake in diamond company DeBeers. Also owns 2 percent of mining giant Anglo American.

3) Nassef Sawiris, $4.75 billion as head of Egypt’s biggest public company, Orascom Construction. Also building a fertilizer plant in Brazil.

There’s no shame in founding a company that does the sort of work no one else wants to do. Commercial cleaning franchises, for instance, often make Entrepreneur magazine’s list of the top franchising companies in the country. Copying an idea that’s proven to work and steadily growing your earnings year after year is the surest way to getting rich. And starting a franchise (rather than going off on your own) should help you avoid the pitfalls most rookies make (see our list of the Top Five Cheap Franchises to start $10,000 or less for some ideas).

One other thing to note: the richest men in Africa (and I can say men because there are no women who made the “top 40″ list) are old. They have an average age of 61, according to Forbes. That’s another aspect to getting rich that a lot of people don’t want to admit: it takes a hell of a lot of work and a hell of a lot of time.

One of my high school friends recently left his cozy corporate job to start a software company. It’s doing well, but he’s hardly sleeping. I get emails from his at 4 a.m. He thinks he’s getting an ulcer and his back hurts from “sitting all the time.”

Some weeks, he bills his clients more than 100 hours. That’s 14 hours a day, seven days a week. I ask him why he’s doing it, and he says “I have a plan. I’m going to trash my body for six months and make this work.”

“What if it doesn’t?” I ask.

“Then, I’m going to close down the business and go back to corporate America.”

At least, he’s trying, and that’s what separates him from almost everyone else I know. He’s willing to put in the hours that it takes to reach a goal – even at the expense of a social life and perhaps his health! It’s a tough trade-off, and it’s probably a pretty extreme example, but I think it’s the key to making lots of money.

It’s hard work, and it’s doing the things no one else can or wants to do.

Photo Credit: Nbauer.

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