It took me until my twenties to build an actual tooth brushing habit. Years and years of parents hounding me to brush after breakfast & dinner, painful years having to also brush after lunch at school because braces (and mostly not doing it), years & years of 6 weeks managing each night then a long stretch of not brushing at all, years & years of frequent cavities...I had a years-long stretch of good brushing broken by one night being too exhausted to brush & just didn't brush at all for the longest while ever...
I could not tell you what exactly helped me transition, but I can tell you various pieces
I switched from trying to form a habit (which I feel stressed about doing and guilty if I don't do it or don't do it well) to trying a routine
Habit vs Routine: EG breakfast as a habit: make exact same meal each morning at same time regardless of hunger/activity/interest, feel bad about changing things up VS breakfast as a set of routines: cereal routine, get bowl, milk, cereal, spoon, pour, eat, take care of dishes; eggs routine: fry/scramble/whatever, eat, dishes; in a rush routine: grab 2 granola bars & a fruit & rush out
I bundled "habit" tootbrushing into the "going to bed" routine; routine is more flexible than habit & leaves room (and acceptance and no guilt) for adaptation
So like, standard I'm not exhausted just ordinary going to bed routine: go to bathroom, use toilet, wash hands, take out contacts, floss & brush teeth (thoroughly), put in retainer, then go to bed, lotion dry hands, turn out lights, sleep
Routine for when I'm dying of exhaustion: toilet, eyes/contacts, cursory brush, sleep
It took a long time, but eventually I wasn't having to remember to brush my teeth separately--I'd be tired and telling myself I'd let myself skip tooth brushing and initiate Goint To Bed and find myself brushing anyway because hey I'm in the bathroom there's the brush oh I'm just Going to Bed and brushing is a step of that
Call it a routine, call it task bundling, call it operative conditioning, whatever
I still don't *wash* dishes as a part of my Eat Meal routine which irks my housemates/parents but whatevs, 1 battle at a time
I want to close on a certain note, which is a How to ADHD book by a psych professional living with ADHD, and which I actually found helpful, but I am having trouble finding the title even searching back through all my reading history on 2 apps so....bear with me and I will either edit this post or reblog again. It was a book I heard about from @thebibliosphere first so I dunno maybe I'll chance the tumblr search function