I try to emulate the views of an impartial person in internal monologue. I think it helps to engage in a lot of debates and discussions and take pains to observe the differences between people who have incentives to engage in motivated reasoning and people who don't, so you can notice in yourself "That doesn't seem like a way I'd respond if I weren't engaging in motivated reasoning," or "that really does seem like what I'd expect from an unbiased person."
Sam Harris, in his recent article called The Fireplace Delusion, tries to make you feel what it's like to react to a cached belief being irreparably destroyed. Just incase you forgot what your apostasy (if you had one, of course) was like in its early stages.
What are some of the Fireplace Delusions you've come across in your days?
EDIT: WOODSMOKE HEALTH EFFECTS