Another good one from HBR, this time about "completion bias." Completing tasks, however small, gives us pleasure, so we tend to do simple and sometimes meaningless tasks rather than complicated and perhaps far more meaningful tasks.
So is the answer to avoid those simple tasks? Actually, no, because "finishing immediate, mundane tasks actually improves your ability to tackle tougher, important things." So the article suggests planning out your most important work for the day, but then cranking out a few (not too many!) small tasks to get into the groove before tackling your more demanding work.
To that suggestion, I'd add that it's even better if your quick tasks at the beginning of the day are high leverage. Here's a small example. Two days ago, I received an email asking me to approve the design for a sign that we had ordered. Before tackling the important work of the day (it happened to be a long bike ride with my son, but that's beside the point), I sent a quick reply approving the design. Our designer was able to get the sign printed, built and installed today, three days ahead of schedule!