You do wonder - when you are at 28,000 feet, the height that aeroplanes cruise at, when you are struggling to draw breath and every limb aches - why do I do this?

As a professional climber, that's the question you always get: Why, why, why? It's an ineffable thing; you can't describe it.

Go out on a limb. That’s where the fruit is.

Mentorship is an incredibly huge responsibility. And you need to choose your mentors carefully, just like mentors choose their apprentices carefully. There has to be trust there, on a very deep level.

People say, 'Are you insane?' But the most successful climbers are the most calculating, with the most refined sense of risk. They're hyper-conscious of safety. They're the least insane people I know.

When you're climbing something as challenging as Meru, it's all about efficiency. Even a decision as small as what to eat for dinner would expend energy you need for making other, more dramatic decisions.