Simpler is better
As a researcher, I'm constantly looking for a non-trivial problem to solve. It's got to look really difficult, and it's got to be the right "type" of difficult (I'm not going to come up with a quicker quicksort, for instance). It's obvious that solving a difficult problem takes hard work and a lot of thought, so one of the most challenging parts of working on a hard problem is knowing when to throw in the towel and move on.
What I just realized (after my advisor pretty much pointed it out to me) is that it's just as important to find a seemingly trivial problem and ponder why it isn't trivial. This is not the same as taking a trivial problem and adding extraneous constraints to it until it's no longer trivial. Rather, it's more about taking a problem and delving into the details of the solution.
I'm going to see how far I can push this. From now on, I'm only going to tackle the easy problems.