A Harvard professor says he knows the secret to happiness and is ready to share it with the world.

Unfortunately, nobody believes him.

The secret, according to psychology professor Daniel Gilbert, is to ask a total stranger.

"In some common situations, surprisingly, the best way to know what will make you happy is to find somebody who is already in the situation you're contemplating and see how happy they are," Gilbert told CTV.ca in a recent interview.

"Obviously, you and other people are different but the differences between people seem to be relatively small."

In one experiment, women predicted how much they would enjoy a "speed date" with a man. Some women were given the man's personal profile and picture while other daters only learned about the man from a previous woman's experience.

"What the studies show is that when you base your prediction about how much you'll enjoy a date on the experience of a total stranger you're 50 per cent more accurate than if you look at the person's profile and see their photograph," Gilbert said.

He said a person's imagination is "prone to error" so when that person imagines a future event they make a whole variety of mistakes.

"Because imagination is so poor you can beat it just by asking a complete stranger who has actually had the experience so that you don't have to imagine it yourself," Gilbert said.

Although Gilbert's study has finally produced a method for people to increase the accuracy of whether they'll like something, he said nobody's listening.

"Most of us feel that if we had some information about the future we could make a pretty good guess about how we're going to feel when we get there," he said.

"A decade of research shows that that's simply wrong."

In his speed dating experiment, Gilbert said the women who had more accurate results by reading someone else's experience still didn't believe his method really worked.

Gilbert asked the women what information they'd like to have if they were going to speed date again.

"Virtually all of them said 'I'd like to see the person's photograph and see their profile,'" he said.

Still, isn't there something to be said about making mistakes?

Gilbert doesn't think so.

"I'm not a big fan of mistakes," he said. "I think something that can save us from mis-predicting is a very valuable thing and I don't think there's nearly as much value in getting it wrong as there is in getting it right."

Instead, he said people should trust their own imagination less and trust other people's experiences more.

"Don't fall for the mistaken idea that you are so different from other people that their experience has little to teach you," Gilbert said.

"You and other people have a lot in common."

So, if you want to become a lawyer, stop daydreaming. Instead, go find a lawyer.

"All you have to do is find one person who is a lawyer and you're already going to have more information about what it's like to be one than you could ever generate on your own," Gilbert said.

"That's not just true for being a lawyer, it's also true for moving to Cleveland, eating apple pie, marrying Andrea, and every other thing that you can possibly name."

But what if nobody else has been married to Andrea?

"Well then you're out of luck aren't you?"