Gradually expanding your comfort zone can help you overcome social anxiety too, says the climber. Relying on alcohol is cheating: you’re not overcoming your fear, or getting to the underlying issues, you’re just “medicating them away”. Instead, you should approach this aspect of your life in the same way you would physical training and say, “This weekend I’m going to the pub, I’m not getting drunk and I’m going to force myself to speak to three strangers.”

Alex Honnold free solo climbing El Capitan. (National Geographic/Jimmy Chin) I was in a very high consequence position Alex Honnold

2. Prepare, prepare and prepare some more

In 2008, Alex free-soloed the Half Dome, another infamous Yosemite landmark. He admits that choosing not to prepare was a near-fatal mistake. There were a number of moments during the climb that were "fraying" him mentally: “It was all sort of coming apart a little bit,” he recalls. Then, on nearing the end of the ascent, he felt unable to trust the foothold in front of him and started to panic. He managed to compose himself and continue to the top, but admits it was horrifying at the time. He realised that he needed to plan properly if he was going to attempt El Cap.

Alex’s preparations lasted two years and were intricate and extensive. The hardest section of the whole route would be the so-called "Boulder Problem”, which culminated in either a leap or a karate kick move. He did various stretches to improve his chances of success: “The more flexible I was, the more comfortable the kick felt.”

Alex says the Free Solo film shows how dedicated he was to the pursuit of that particular climb. When the day finally came, he was "totally ready for it".

3. Imagine and visualise

An element of Alex’s preparation was to rehearse the climb in his mind. Partially, this was memorising where he would place his hands and in what sequence. “But then the real visualisation is the deeper level,” Alex explains. “What will it be like to look down into the abyss while I put my foot on to this tiny, tiny edge and then trust my life to it?” By thinking things through, he "wouldn’t have some moment up on the wall where I suddenly experienced something that I’d never thought of before, that I’d never imagined."

“The other real strength of visualisation is to imagine all the things that won’t ever happen, or that you don’t want to happen… I was also visualising what it would be like for my foot to slip and for me to fall to my death; or for me to do the karate kick but to miss it.” You want the full spectrum of experience just so nothing is a surprise, he says.

“It’s easy for fear to creep in if you just don’t know what’s going to play out. But if you’ve already thought through all those different what-ifs, I think there’s less room to be afraid.”

4. Practice makes perfect

When Alex was younger he was horrified at the prospect of public speaking; he went through a year of university scared to talk to strangers; and even as a professional climber he was gripped by fear and anxiety when giving slide shows. But practice has made interactions like these easier.

Alex also admits he's had issues when it comes to dating. "At some point you just have to force yourself to do the thing, and just practise. You just go over and say hi. Because it gets easier to do that, the more you practise.”

Alex applied the same approach to climbing El Cap. He spent hundreds of hours on the granite face, attached to ropes, precisely choreographing and rehearsing each section. He practised the Boulder Problem around 60 times before his free solo attempt and the "Freeblast" – where he had to smear his shoe against smooth rock and maintain perfect balance – as many as 90. “I had already completed that climb with a rope many, many times. I knew that I could physically do it.”

5. Differentiate between legitimate fear and unfounded anxiety

Alex believes we need to differentiate between real, justified fear and what is just vague anxiety. “Changing jobs can feel like you’re going to die – it can be super scary,” he says, “but the reality is that you’re not in any danger.”

Crucially, with the two years of preparation he didn’t feel like he was in danger any more. “I was in a very high consequence position - had anything gone wrong I would have died, but the likelihood of anything going wrong felt extremely small to me… It felt like close to zero.”