Why is it so hard to be happy? One reason is that we're bad at predicting how our actions will make us feel. Doing "whatever we want" often winds up making us less happy than some other course of action that at first blush might seem relatively unappealing.

In my case, I think about all those lazy weekends during which I've looked forward to around, doing nothing -- an state of affairs that seemed very appealing when I got up on Saturday morning, but which by twilight on Sunday left me feeling like a pathetic sad potato.

Fortunately, this puzzling and irksome phenomenon has been addressed by science, as described in a blog post by the consistently thought-provoking and entertaining BPS Research Digest. Christopher K. Hsee at the University of Chicago gave his experimental subjects a choice between taking a completed questionnaire to a location 15 minutes away, or delivering it right outside the door and then sitting and waiting for 15 minutes. At the end of each task, they were rewarded with a tasty chocolate snack bar.

Here's the punchline: the students who walked for 15 minutes reported feeling happier than those who had stayed put. And it wasn't just because happier people self-selected to take a walk -- even when the test subjects were told to wait or walk with no input into the choice, the walkers reported feeling happier.

Hsee concludes from his experiment is that people have an instinct for idleness. Given the choice between doing something that requires effort, and doing something that simply requires us to sit on our duff, most of us are going to choose the duff. What's fascinating is that the duff-sitters in his experiment made a conscious choice between two potential courses of action, and they chose the one that made them less happy.

How could that be?

One possibility is that we simply don't know ourselves very well -- that the sitters honestly but mistakenly believed that sitting would make them happier. But I don't think that this is the case. Rather, most of us make decisions not based on what will make us happy in the future, but according to impulses that are entirely in the present tense. Right now, in this exact present moment, sitting seems easier and more pleasant than trundling off somewhere on a hike, and so I make the choice to sit.

, by contrast, is an emotion that occupies a much broader temporal landscape. We look ahead with anticipation at the good things that are going to befall us, or look back at the impressive things we've achieved. After a 15-minute walk, we feel good about the exercise we've just accomplished. We feel the blood flowing through our veins, the fresh air on our cheeks. While those of us who sit, having chosen the momentary pleasantness of relaxation, wind up feeling only the dull regret of a quarter-hour wasted.

PT blogger Timothy A. Pychyl has addressed the problem of giving in to momentary temptations, especially as it relates to his specialty, . He writes:

Procrastinators will tell you that the task they're facing (avoiding) is difficult, and it creates bad feelings like or general emotional distress. Putting off the task at hand is an effective way of regulating this mood. Avoid the task, avoid the bad mood. This is what Tice and Bratslavsky refer to as "giving in to feel good." We give in to the impulse to walk away in order to feel good right now. Learning theorists would even add that we have now reinforced this behavior as the decrease in anxiety is rewarding. Of course, this short-term strategy has long-term costs... If we focus on our feelings in the short term, we'll undermine ourselves in the long run.

And now we come to a twist in Hsee's experiment. When the students were told that they could get a different treat if they chose to walk, the majority got off their butts -- even though the treat was objectively no better than the one they would get if they stayed. To Hsee, this is evidence that we all unconsciously crave busyness, and need only the mildest prod to undertake it, as he explains in a story on the website of the Association for Psychological Science:

Hsee believes we can use this principle - people like being busy, and they like being able to justify being busy - to benefit society. "If we can devise a mechanism for idle people to engage in activity that is at least not harmful, I think it is better than destructive busyness." Hsee has been known to give a research assistant a useless task when he doesn't have anything for the assistant to do, so he isn't sitting around the office getting bored and . "I know this is not particularly ethical, but he is happy," says Hsee.

I wonder, though, if it's possible to use this strategy ourselves. It's one thing to tell a subordinate to undertake a useless task; I would find it very hard to motivate myself to undertake a project that I knew was pointless busywork. On the other hand, doing the laundry, mopping the floor, or mowing the lawn are useful, if mildly unpleasant, tasks that I know will make me feel better than wasting an afternoon watching old movies and eating KFC -- if I can just get myself to do them.

The trick might be different for each of us, but one approach might be this: to consciously try, during those crucial moments of decision, to keep in mind not just how our actions will affect us in five seconds, but in fifteen minutes -- and beyond.