You want to be working right on the edge of your abilities. If you're in your comfort zone you aren't going to learn anything new. If you're completely in over

You want to be working right on the edge of your abilities. If you're in your comfort zone you aren't going to learn anything new. If you're completely in over your head, you'll just flounder. Working right on the edge lets you make the incremental improvements in your skills that can take you to excellence.