The first thing I did when I sat down to work today was do the easy stuff on my list that does not need to be done until the end of the week. Then, when I should have been going to bed, I started working on the stuff that has to be done today.

I know that I do this a lot, so I have started implementing tricks to stop myself. Like, I categorize everything on my list as an A, B or C, and I have to do all the A’s first. Sometimes I’ll give myself a little gift and do an easy C for a break. Steve Pavlina has written a treatise-length blog entry on the perils of doing the unimportant tasks first. I am hoping that will inspire me.

But research shows that we procrastinate because we are hard-wired to be time optimists; we overestimate the amount of time we have left to do a project. According to Gal Zauberman and John G. Lynch in the Journal of Experimental Psychology, we think we’ll have more time in the future because each day is different, so the nature of time fools us. But in fact, the amount of time we have today is probably the amount we have in the future. If you’re busy today, you’ll be busy then.

Alex Williams in the New York Times points out that this is such a big problem that we are frequently relieved and even euphoric when someone cancels on us: “In the Age of the Overwhelmed the cancelled date is a luxury gift.”

People also overestimate how much money they’ll have in the future, but the problem is not nearly as bad with money as with time. Our expenses are more often set in stone than our time commitments, so there is less room for us to poorly estimate the variables.

So recognize when you are looking at your to do list that you have less time than you think you do. And maybe you should only accept invitations for something you’d be willing to do that day, even if it isn’t scheduled for that day in reality.

But Harvard psychologist Daniel Gilbert gives us encouraging news in his book Stumbling on Happiness: The people who overestimate how much better the future will be are actually the happiest people. So maybe being realistic about our time is not so great after all.