I would recommend some kind of "zen" type of meditation as well. It doesn't have to be the religious type (i.e. the lowercase Z suffices) but learning to stop t

I would recommend some kind of "zen" type of meditation as well. It doesn't have to be the religious type (i.e. the lowercase Z suffices) but learning to stop thinking and accept the present moment for what it is without preconcieved notions can be incredibly useful for spotting assumptions when one is thinking and, consequently, for improving the quality of ones thoughts. It also helps with planning for the future and analyzing the past. Bad assumptions seem to be at the root of most stupidity and zen style meditation is excellent for learning to cope with them.