Toothpaste
For the longest time, barring exceptional circumstances, I would only brush my teeth once a day. Because mint toothpaste causes me physical pain and the overwhelming aftertaste wouldn't go away for a good hour afterwards, preventing me from eating breakfast. So I just didn't brush in the mornings unless I had an external need to, like going to the dentist.
When I was really struggling with my mental health I sometimes couldn't manage to brush every night, either. It was somewhat of a fraught activity for me.
I'd tried various normal brands to see if there were any I could tolerate better, but tended to just find more that I couldn't tolerate at all (in short: anything promising "extra fresh breath").
Then I found out, via this webpage that actually I could just use kids' toothpaste. I assumed that anything marketed as "3-8 years" would have less fluoride than normal "adult" toothpaste, because 3 is pretty darn young, but not so.
It tastes exactly like chewing Hubba Hubba strawberry gum, including the undercurrent of flavourless gum aftertaste. My husband found it absolutely disgusting when he tried it and had to follow up with normal toothpaste afterwards, but for me I don't think it's too much to say it's life-changing.
Actual dental hygiene!