There was an interview at TrackShark with Illinois runner Angela Bizzarri, runner-up in last year's NCAA 5k (15:46!). She addressed the topic of success breeding pressure vs success breeding confidence:
Does your past success put pressure on you to perform or does it fuel your confidence for upcoming races?
AB: It definitely helps build my confidence. You can get in really good shape and have great workouts but a lot more of it is mental. You have to know you can hang with that top pack. Seeing that you can gives you that mental edge that you can do it again.
The hardest dip to get through as an elite runner (or a pre-elite runner, I should say) is having that confidence that you can, in fact, hang with your competition. I imagine it's the same for a fresh lawyer entering the court before his first high profile case, or a doctor performing some complicated new surgery before the eyes of his fellow surgeons. Doing it the first time is terribly difficult, but after that, it gets easier and easier.
There are ways to gain that confidence that don't involve having that experience, though. The first is to work with people who've done it. That demystifies it and demythifies it. This is why people who apprentice under an artist or who join a team with a senior champion on it tend to excel. The illusion that success comes from talent is shattered when the work ethic of the expert is laid bare.
Another way to gain in confidence is to frame the challenge in the terms of your previous success. For example, I'm studying Italian right now. I don't know any Italian, but I do know Japanese. The simple fact that I made it through the dip in Japanese gives me the confidence to know I can do the same with Italian. Finishing third in my league in cross country gave me the same kind of confidence when I started running track that next spring. Sure, they're different. But it was the similarities that mattered.
The last way you can improve your confidence is to simply take a risk and have it pay off. This can be tough, though. Taking a risk in running generally means executing a strategy that will put you through increased pain with increased probability that you will not succeed. And if you are mentally ready for that potential failure, it can be much worse than simply playing it safe. But when you do succeed, it can completely change your perspective on what you can do.