If you have kids or you remember when you were one, you know that patience is a virtue. Imagine being one of these four-year-olds staring at a marshmallow for 20 minutes to earn the reward of an additional sweet treat?

This “Marshmallow Test” is a test to see which kids are able to defer gratification.

In the Wall Street Journal, Arthur Brooks, president of the American Enterprise Institute, writes that in a 1972 test, the children who didn’t take the marshmallow “were less likely to drop out of college, made far more money, were less likely to go to jail, and suffered from fewer drug and alcohol problems.”

He goes on to write:

When we hear about successful entrepreneurs, it is always as if they had the Midas touch. A pimply college kid cooks up an Internet company during a boring lecture at Harvard, and before lunch he's a billionaire. In real life, that's not how it works. Northwestern University Professor Steven Rogers has shown that the average entrepreneur fails about four times before succeeding.

For many entrepreneurs, the journey is a reward in itself. Brooks continues:

When asked about their ultimate success, entrepreneurs often talk instead about the importance of their hardships: early failures and bankruptcies, missed Little-League games, endless nights without sleep. They talk about almost losing their home and the strain all this put on their marriage. When I asked the legendary investment company founder Charles Schwab about the success of the $15 billion corporation that bears his name, he told me the story about taking out a second mortgage on his home just to make payroll in the early years.

Why this emphasis on the struggle? Entrepreneurs know that when they sacrifice, they are learning and improving, exactly what they need to do to earn success through their merits. Every sacrifice and deferred gratification makes them wiser and better, showing them that they're not getting anything free. When success ultimately comes, they wouldn't trade away the earlier days for anything, even if they felt wretched at the time.

In an essay on FreeEnterprise.com Brooks connects this journey to the pursuit of happiness:

It means the right to define and earn our happiness through our ideas, hard work, and gumption, to earn our success by creating value honestly, in our own lives and in the lives of others. It doesn’t mean the pursuit of a big lottery win or an inheritance. Those bring money, but not happiness. And a mountain of evidence shows that after a fairly low threshold, more money doesn’t make us happier.

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In short, the secret to the pursuit of happiness is earning our own success; creating value with our lives and in the lives of others. This earned success is the fruit of hard work and just rewards in a system built on merit. Only in a free enterprise system is effort and innovation rewarded over connections and predation.