Hi,
1) Can some of those "projects" go on your "someday/maybe" list, at least for now?
2) Have you checked out David's new weblog at david.davidco.com yet? His entry on March 24th, "Working a decision-support checklist", might help.
3) Would it help to take more frequent breaks, or rotate between this and other tasks? When I started GTD, my head would hurt after as little as 5 minutes. It's a new way of thinking, and got easier with practice and experience.
4) I've found it helps to describe the successful outcome in its own sentence(s), using as many words as I need. Here's an example:
Think about whether to go to D.A. "Leveraging Focus & Vision"
seminar on Boston on Fri. 5/14/04
Success: Decide whether to go, or pass 'til next year
ent'd 1/19/04
5) Are you aiming for "perfection"? One of the greatest things about GTD is its flexibility. As David puts it, we're free to "re-negotiate our agreements with ourselves" as much as we need to in order to feel good about them. For me, that means starting simply, just getting "stakes in the ground". Then GTD puts time on my side, letting things come into focus naturally as I look through my lists each day.
Hope this helps, and have fun,
Tom