More seriously, ADHD, among others, is a working memory disorder. A way to cover this is to use “prosthetics” for it, such as a notepad that you always carry with you. If this affects you strongly, train your muscle memory to use it to note down what you were planning to do and to refer to it when you forgot.
In PC-speak, ADHDers have traded RAM for more CPU.
Paper notepad wouldn’t work for me due to awful fine motor skills (another ADHD symptom) making my handwriting slow and cumbersome. I can write probably three times as fast on my phone where I just have to tap the letters rather than use dexterity to shape them, thus making it much less of a “stupid hand can’t keep up with my brain” kind of frustration thing.
Plus back before smartphones were a thing, I always walked around with so much junk in my pocket that the notepad would take quite some time finding and fishing out, if it would even fit 😂
Of course one solution doesn’t work for everyone. if you current system works for you, keep at it. I know for me, fishing the phone out my pocket, unlocking it, opening a notepad app, opening a new note and typing it badly, is probably as slow as a notepad at least. And then due to the nature of the phone, I forgot I had notes.