I believe some of the hardest jobs in the world involve being creative or inspired, “under the gun.” That is, required to come through with something remarkably perfect on a tight time schedule. The problem with these jobs is that very few people are such optimists that they believe they can come through when required. There's no way to check your mental equipment and know that it's in top gear when you want it. The inevitable doubt takes its toll. I'll give you two quick examples here.
The first is Reggie Jackson's remarkable day when he won a world series game by hitting three home runs with three swings of the bat. He may have been lucky, but he required near perfect concentration to turn three swings into three home runs. When he woke up that morning, did he tell himself he was in perfect shape to go? I doubt he had any way to tell. Jackson was called “Mr. October” for his ability to be at his best in the world series. I suspect he didn't know how to “be at his best,” or he would have been there most of the time. Some of baseball's clutch hitters also had lots of psychological problems, maybe, just maybe, stress-related.
In baseball, you can be a wildly successful batter if you do what you're trying to do one third of the time. The other two-third of the time, great hitters fail. Yet there have always been clutch hitters who came through more often when really needed. Do they know, when it's the last chance to win a game, that their timing and perception have stepped up to the next level, ready to turn the miracle? How could they know? What they do know, is that everyone is counting on them.
The composer, Richard Rogers, is my other example. He composed hit musical after hit musical, and wrote a lot of other very popular music. All he needed to do, to keep his family in the style it was accustomed, was to write another hit musical. How do you know you're going to write another hit musical? I think you don't. But if you want to get up in the morning and put pen to music paper, you've got to take yourself deeply on faith. Rogers was not always a real nice guy. The pressure got to him.