Merlin Mann, author on 43folders.com has written an excellent piece on the use of priorities in your life and your Next Actions list. Definitely worth a read and a save in you rreference folder.
The truth is that sometimes you have crap days, pencils need to be sharpened, or maybe you just dont have the tools or energy to do what you want the second you want. Thats life, pal. Deal.
Make sure you also read the comments on some more insight on this subject.