The fear of running at the front, is that if you fly too high, you have a long way to fall. But if you run from the back, your confidence gains it's rank without risk. And the psyche deals with gain much easier than it does with loss, no doubt. So it is better in the warmup races to run from the back and experience the freedom of pressure and the pleasure of understanding where one belongs. But not so much as to forget the responsibility of pushing yourself to your own limit and letting the rest try to match up.