I think that's a good description and I believe it is both of those definitions you offer. I think courage fits in the definition somewhere too.

But if we limit the definition here to the will to survive, or even broaden it to the drive to continue on, in situations related only to backpacking, than I still have to say I have not been tested, at least not very hard.

I've always approached backpacking and hiking as a leisure sport, never an extreme sport. I don't approach it with a survivalist mentality either. That's not to say I don't think the skills cross over, or that I'm not interested in learning and practicing survival skills. They do, and I am, but that's not why I backpack or hike.

It's never been a matter of testing my mental or physical toughness. Not at all. It's always been to seek solitude, and peace, and nature. Possibly even, at a deeper level, to get away from having to be tough.

I've gotten cold, hot, cut up, knocked down, scratched, bitten, wet, tired and hungry while hiking and backpacking, but I've always loved it, so it was never tough. Not a single time have I ever thought "I wish I weren't here". I can't count the times I wished I could've stayed longer. Honestly, leaving has sometimes been mentally tough.

Now, because I love meandering around and sleeping in the mountains, I cannot judge the mental toughness of those that don't based on how they react to it. I display none of the characteristics defining it above when I'm invited to sit in a nightclub for hours and I do retreat into negativity, panic and despair when that happens. There have been a lot of times when I went in thinking I could tough it out and couldn't do it. I'm not near tough enough for that.

So, when it comes down to it, I'm not sure that mental toughness really has anything to do with backpacking.

I don't mean to imply it's not worth discussing here, I'm enjoying the conversation, but I think that in terms of how often it actually applies to backpacking it's probably not uniquely relevant.