An odd little app, this one, but unlike most odd little apps it really does work. I suppose you might call it the front-end to a psychological theory of how attention (focus, productivity, call it what you will) actually works, rather than how it *might* work.
Like the celebrated (and, to my mind, rather overwrought) GTD, Vitamin-R adopts, and tries to enforce, a simple principle: AIM LOW.
Don't say "I'll devote the next five years to writing that Great Novel". DO say "I'll devote the next fifteen minutes to writing the opening of Some Novel Which May Possibly Be Just About Okay."
Vitamin-R keeps you on that track. Fifteen minutes in, it says "Take a break". I find after a couple of weeks that 80% of the time, I'm overriding it, and saying "No! I want to keep working! Give me another 15 minutes!".
It's a simple idea. So are the basics of human reproduction. The process, in both cases, is diverting, and the results, in both cases, rather impressive. Highly recommended and as a previous poster said, saved me the cost of buying a licence first time I used it.
Oh, and the developer is *very* responsive.