Ask YC: How do you achieve laser focus and concentration?

Reading the news.yc item about Provigil and reading more about it, I'm convinced that it's the kind of thing that gives you laser focus and concentration. Silver bullet drug, really (see http://www.erowid.org/experiences/exp.php?ID=62958)

Since it has strange side effects and U.S. restrictions (requires prescriptions), I'm wondering how you achieve concentration and focus when doing work.

I'm interested in this in the context of concentrating in class, doing schoolwork, and hacking.

Thanks.