Nobody wants to think about mental fitness. It's a lot easier to keep track of physical improvement than mental improvement. To become stronger mentally you have to look inside yourself and realize that, even if you can do a one-arm pullup with an engine block in the other hand, the ultimate limiting factor is your head And most people are simply too weak mentally to actually get stronger mentally. For many people the area between their ears is completely dark, off-limits and filled with soul-twisting demons that just can't be faced much less slain. But, unless you know how to hit your ideal mental performance state, all your training is quite literally a waste whether your competing at a world-cup level or trying to set a PR of some kind.
When I was competing in a lot of sport climbing comps I had a reputation for climbing "above my ability." This is debatable, as people tend to remember the successes far more than the failures (nobody remembers me falling off the third move at a world cup in Laval, France--I sure do). Anyhow, I think I could climb at my trained ability in a comp while most people couldn't. Same with onsighting. It's not about doing something special in a comp or high-stakes environment, it's about doing what you've trained to do and do in training. That simple.
So how do you train mentally? At a basic level, I try to train like I compete, and compete like I train. That sounds so simple, but very few outdoor athletes do it. I would also include any sort of "goal day" or GD under the competition level. If you're going to try and redpoint at a high level or set a new PR on the Grouse Grind (look that up if you don't know it, fun!) then you need to set up situations that mimic what you're likely to find, and then deal with it. Simulations don't have to be perfect and never will be, they just have to elicit the same sorts of feelings and stress you'll be competing or going after a GD under.
These simulations can be entirely mental; I often go and look at a venue I'll be competing in, and then sit someplace and quiet and populate the stadium or environment with people, a challenge, problems, and noise, distractions, etc. When I walk out to throw down very little surprises me... If I don't do this kind of prep I often do poorly.
There are many, many books written on mental training, and I have read many of them. Some are hokey and full of mumbo jumbo, but a few are good. I'd rather not endorse books publicly (other than my own, grin...) but drop me a private email and I'll respond. A few key ideas in good mental training regimes:
1. Worry about the things you can control, and get them right.
-Don't show up with your blown-out laces about to break. Be well-fed, well-hydrated, well-dressed, etc. etc. This a really deep well to look down once you get going on it...
-You can't control other people's results, or even your own. You can only control how well you perform... If you perform well you'll get a good result, but worrying about the result is wasted energy. We all want to win, but you can't control that. You can control how ready you are to compete and prepared to get a good result...
2. Nothing is ever perfect in a high-stakes situation. Deal with it, stay focused on competing well. Things will be messy; this is life, competition, solve the problem and move forward. Easy to write, hard to do.
3. Know what your head feels like when you are competing well, and get to that place.
-I often get very negative before big comps. I don't feel trained, don't feel excited, worry about failure, etc. etc. But I know that if I sit down in a bathroom stall for about 15 minutes I can generally pull this together and get into my preferred comp state... Not always, but about 90 percent of the time. Everybody needs to get to their performance state differently, but get there we must.
4. Do your best in training and in competition.
-Never accept less than your best possible effort. Some days you will be tired, sore, distracted, hung over, whatever, but do your best. You know when you do your best, when you leave nothing on the table. Sometimes my best isn't much, but if I've done my best then fuck it, that's all I've got. I have also not done my best in competition, and I still get pissed about those days when I left a little on the table...
Fundamentally I believe in training my weaknesses. Finding those weaknesses often takes more personal honesty than I may have on any given day. It's a lot easier to bang out another set of pullups than it is to admit I have the contact strength of a fish... In almost all situations your head is the limiting factor in performance, not your body. You do need to be trained, but if your head explodes at the sight of a starting line then what's the point?