The problem with spending the time to figure out your purpose, and then spending the time to follow that calling, is that inevitably, it will feel like the craziest, stupidest thing you’ve ever done.You’re going to spend a lot of time in doubt—questioning yourself, your plan, your calling and everything in between.

“Why would anyone do this?”

“Why would anyone hire me to do this?”

“It makes sense on paper, but it probably doesn’t work in real life.”

“I’ll never get this to work.”

“Maybe I should just go do something safe instead.”

Anytime you’re in this circle of doubt, doubting what you really, really want to do with your life and straining against all the reasons why it’s the stupidest move you’ve ever made, but pushing forward anyway, I want you to remember one thing:

The Pet Rock.

In 1975, Gary Dahl, an ad copywriter, invented the pet rock. And by invented, I mean he took rocks (things that already existed) and sold them (presumably, to people who could have just picked up a rock in their front yard) for today’s price equivalent of $20 a piece. (They were $4 back then. I’ll leave you to the math.)

In only a year, the Pet Rock was discontinued. But by that time, Dahl was already a millionaire.

Off of rocks.

What’s important to realize is that Dahl didn’t create anything new. But he also didn’t redo someone else’s idea—only better. All he did was sell the vision. These weren’t your everyday rocks—they were of a rare, exotic breed (from Mexican beaches). They came with their own carrier (complete with breathing holes and soft bedding because…you know…it’s a pet). But more so—he capitalized on the emotions and needs of other people at that time.

He told People magazine, “People are so damn bored, tired of all their problems. This takes them on a fantasy trip – you might say we’ve packaged a sense of humor.”

So next time you’re feeling like you’ve just made the stupidest decision in the whole world, or that no one will buy what you were put on this earth for, just remember: Someone bought a rock for $4 to get a laugh and in turn made someone else a millionaire.

I promise your idea isn’t as crazy as that.