Writing down precise predictions is like spaced repetition: it’s brutal to do because it is almost a paradigmatic long-term activity, being wrong is physically unpleasant, and it requires 2 skills, formulating precise predictions and then actually predicting. (For spaced repetition, writing good flashcards and then actually regularly reviewing.) There are lots of exercises to try to (calibrate yourself using trivia questions obscure historical events, geography, etc.), but they only take you so far; it’s the real world near term and long term predictions that give you the most food for thought, and those require a year or three at minimum.
http://www.gwern.net/Prediction%20markets