I had things that I "could do" mixed in my context lists with the things that I "had to do".
I realized that "could do" items belonged in one of the following places:
a) with projects that belong on the someday/maybe list and therefore aren't ready to be on a NA list.
b) on checklists or other separate lists (what to do if you have 5 minutes in your office for example, list of spots where papers accumulate that I'd like to clear up. Don't need the whole list of places on the NA list.)
3) didn't need to be on a list at all because they were things I will do instead of things I "have to do" if I don't keep focused on the NA lists (for example, surf the web, read for pleasure, watch a favorite tv show)
Keeping my lists strictly to "have to do" makes them much more "doable" for me.