Swearing
I have developed an icky habit of letting loose a few expletives in my head when I'm particularly frustrated or irritated.
It's not so good for me, and it's not good for anyone else around me if a word accidentally slips out.
I've been a little convicted about it, and have been trying to work out how to get rid of it.
A cheesy rhyme sprang into my head the other day and now whenever I start to get mad, I think: "Swap swear words for prayer words."
It's groan-worthy, but it's working.