This reminds me of Lykken's First Law:
The quality of one's intellectual productions is a function of the product of talent (e.g., intelligence) times mental energy. Although there are many and varied tests for assessing intelligence, psychologists have not as yet even attempted to construct a measure of individual differences in mental energy.
David Lykken proposes in this editorial (gated) that psychologists should take up the study of mental energy. In particular he makes the falsifiable claim:
Mental energy (e)–the ability to persist for long periods thinking productively about a problem, the ability to focus attention, to shut out distractions, to persist in search of a solution–is perhaps as important as general intelligence (g) in determining both successful performance and constructive achievement and the product of these two variables, g*e, provides the most valid predictor of success and achievement.
I haven't been able to find any study done on this though. Please share references if you find any.
One of the big variations I see between people is the amount of energy they habitually put into thinking, and I haven't seen this discussed anywhere.
General advice about improving health and lowering intellectual friction would seem to help increase the ability to think, and ideas like "take five minutes to consider the problem" adds impetus, but I'm not sure what the general difference is between me and most people, or Yvain and me.
Intellectual drive isn't an unalloyed good-- cranks have high drive combined with low self-editinig, and some types of depression include a compulsion to think about topics that cause misery and/or inertia. Part (all?) of the value of meditation is getting some time off from thinking. Still, increasing intellectual drive would probably be a good thing for a lot of people.
Has anyone found that rationality training or anything else increases the default desire to think?