Why is procrastination seemingly part of our culture? Much has to come from our deadline-driven conference and grant system. If deadlines motivate us highly then not having a specific deadline for a task (say writing or refereeing a journal paper) tends to push that task down to later when we'd rather be doing something else like research.
Sometimes people take it to the extreme: One time someone decided to skip a workshop months in the future because a STOC deadline was at the end of the same week. I convinced that person to sign up for the workshop by tricking them into thinking the deadline was one week earlier. Maybe I lied but wasn't everyone better off for it?
And then, of course, as computer scientists we are always on a computer with access to the web, the great distractor. It's just too easy to catch some videos, catching the latest political news, reading and writing email and blogs…OK, back to work for me.
Enjoy the 4th everyone and we'll be back on Monday.