Pre-cellphone I would keep a little 2x4 notepad in my pocket with a pen, as I tend to get an idea and think "oh yeah! I should do that!" and then I see a butterfly and wonder off after it, and totally forget. So the notepad would accumulate ideas or to-dos, and the page would be tossed once done.
Now with a phone I have the free Evernote app installed to keep various notes including a to-do, grocery list, and long term project ideas like building projects at the Lab next year. It also has an option for taking pictures or recording an audio note to insert, and as I've begun the clean-and-prune phase in my house to downsize prior to moving, I've come across old items that have sat in boxes for decades untouched. So now I figure I can take pictures of those things to save online, and then toss out the original when it's only the thought/reminder of the past event which counts.
I found that a list of "organize to-do" items can also help when times are stressful or the list gets overwhelmingly large, and your brain starts to avoid that additional source of stress. I make that list into 5-10 minute items, and then maybe do one a day knowing "it's just 5 minutes", and by the end of the week the list is gone or is still smaller and not overwhelming.
Having a place for things really helps, I have a room of stuff that is mostly items I no longer use and need to donate or toss if it's broken. Normally I don't go in there so items sit ignored/forgotten. Same with a corner in the garage, this weekend I have a note to buy some shelving for the garage to get items off the floor.