(REUTERS/ Anton Ferreira)

We all know the feeling of fear.

Sometimes, it's rational: Clinging to the edge of a cliff, not roped in, you feel the strain on your fingers as your hands sweat and know you need to pull yourself to a safe position.

Other times, it's completely, infuriatingly irrational: Stepping to the front of a room, about to discuss a new proposal, your throat starts to close and your heart starts to pound.

Fear is an imperfect mechanism, a throwback to a time when it would be triggered by real threats likely to kill us. Most of us don't face those threats now, but the same part of our brain, the amygdala, lights up in response to a situation rightly or wrongly perceived as threatening, and something in our brain tells us to take flight, flee, or freeze.

We want our minds to function correctly, and so we can't wish or cut away the biological circuitry that triggers that fear reaction. But over the years, psychologists have developed a strategy that can prevent those moments of fear from becoming overwhelming.

Instead of trying to avoid thinking about what might go wrong, researchers say that carefully rehearsing each potential fear-inducing moment before it happens can help. That way, when those moments inevitably arrive, they aren't a surprise or a shock. Rehearsing the way that certain scary moments will feel means that those moments feel "right" when they happen, instead of feeling surprising.

This psychological technique is known as "mental rehearsal," and it can be used to get ready for anything difficult.

Research has shown mental rehearsal can help doctors perform better. Astronauts like Chris Hadfield say it's an essential part of their preparation for spaceflight. If something goes wrong while repairing a space station part on a spacewalk, they want to already have thought about how they'll deal with the situation.

How to prepare

If you've already thought through how everything could feel, you're prepared if things actually do go south.

Mental rehearsal sounds a lot like the way free solo rock climber Alex Honnold has described his preparations for potentially deadly ropeless ascents of massive cliffs.

"When I'm planning on doing something challenging, I spend the time sort of visualizing what the experience will feel like and what the individual sections of it will [feel like]," Honnold said on a recent episode of The Tim Ferris Show podcast.

"Particularly if it's a free solo, I'm climbing ropeless, then I'll think through what it'll feel like to be in certain positions, because some kinds of movements are insecure and so they're kind of scarier than other types of moves, and so it's important to me think through how that'll feel when I'm up there, so that when I'm doing it I don't suddenly be like 'Oh my God, this is really scary!' I know that it's supposed to be scary, I know that's going to be the move, I know what it'll feel like, and I just do it."