What do we get out of doing difficult things? And how do they make a person tough, or even brave?

Dr. Xander van Tulleken addressed these questions when he appeared on a recent Spartan Up! Podcast. Van Tulleken has tested himself time and time again by travelling to some of the most dangerous places on Earth, providing medical aid in Darfur, Uganda, and Sudan. He and his twin brother Chris were also the hosts of the BBC's adventure program Medicine Men Go Wild. In that show, the van Tulleken boys found the most remote areas on the planet to learn about tribal medicine-and tested it all on themselves.

"I'm always very interested in the idea of people who are gritty and tough," van Tulleken said. "You see CEOs working amazing 20-hour days, cranking them out all the time, and yet, they don't have the self-discipline to manage their weight. Or you see people who are in incredible physical shape, and they don't have a job. They do nothing. Both of those groups are tough in one respect, and yet there's one other bit of their life where they're not tough at all."

It's really important to put ourselves into situations that challenge and stretch us-situations that make us grow, that bust us out of our comfort zone. "Doing hard things doesn't make you tougher," van Tulleken said, "it just makes you not like doing hard things. You know how bad they're going to be.

"But the thing you get out of doing hard things is that you find out you can do very, very much more than you think you can," he said. "So you get a bit of knowledge. With me, whether it's climbing in the Himalayas, or long expeditions in the north of Canada or working in the Arctic, whatever it is, I just have that same feeling of 'Oh, here we go, this is going to be horrible.' But there's also knowing that I can get through something because I've done it before. But I don't enjoy it more than the next person."

"I'd say that I'm more tough than brave," van Tulleken said. "But even then, I'd say it's probably just that I already know I can do something. And, when you're in it, danger never feels dangerous: you're under house arrest and it's really very boring. The most important bit of equipment in an emergency is a copy of The Geneva Convention and a book of poetry. That will help you get your head around who these people are."

Of course, doing difficult things takes endurance. But even that has its own reward. "Endurance should be part of everyday life," van Tulleken said. "In fact, the happiest I've ever been is when I'm doing difficult things."

And that means learning from your failures. "I probably fail at things every single day," van Tulleken said. "I was trying to climb Cho Oyo, which is the sixth highest mountain in the world, and I didn't get to the top. I didn't think that was a failure, because I couldn't even speak by the time I was moved down the hill.

"But I think every day, just crapping things up and being late and missing emails and stuff-those things are really hard for me," van Tulleken said. "Just the basic administration of life. That's what I beat myself up over. People think I'm the kind of guy to wake up at 5am and do email. I don't."

"I need a goal. I get out of shape when I don't have one. It's about motivation and why you want to do it. You cannot be too anal or obsessive about what you're doing.

And even what van Tulleken learns from his failures is good advice for all of us. "Where things have gone badly wrong, it's always about indecisiveness and uncertainty," he said. "When you truly know that things will definitely go wrong, no matter what you're doing, and apply that, you're better off. It's all a frame of reference thing."