My normal reaction when things don't go as planned is to curse roundly, thump something, and try again with gritted teeth. While this approach has served me well on many occasions, I've found that it usually doesn't work for things that really matter. I wouldn't be approaching flying this way if it weren't for my budgetary constraints. The problem is that it's difficult to chill out when you're burning money this rapidly and not seeming to make any progress, if you see what I mean.
I do that too...or I used to. But I've found that I have to split my life into two parts, ordinary life and flying. For the flying part, I refuse to think about how much I'm spending; it takes what it takes, and when I run out of money I stop, at least for a while. It was the only way I stopped being so driven and stressed that I was my own worst enemy when I was learning. Now, as an instructor, I try to teach my high-achieving students the same thing, but it's still hard. Yes, deep breathing helps, so does consciously giving yourself a shake to relax, and similar tricks, but ultimately it needs a fundamental re-assessment of your attitude to flying and life and success and failure. And it's a very useful lesson when you can learn it - I speak from (painful) personal experience.