Mindtraps are circumstances that require you not to think. Or to stop after certain iteration.
Classic, but rather easy to avoid is "do not think about something" mindtrap. Filling mind with static helps.
Better example is two generals vs two canyons. One general has to lead forces through one of them to attack the other, One of canyons has a good place for an ambush. Second general has to place an ambush in one of canyons.
First general: Of course, it makes sense to go through less ambushable canyon. But what if second general sends forces to that canyon too? Then it would be better to choose ambushable one... And here we have a loop. Mindtrap.
Another good example: You are now breathing manually.