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.
@Viking_Hippie @db0 I noticed the other day that my mind has what I call “branch thoughts” that sprout as related but separate thoughts to what I’m currently trying to get out of my head. These branch thoughts usually need to be explored individually but if I do that while writing, the original thought is lost. I usually stop writing down the ideas all together because it’s just too much going on at once.