I know what you mean. I tried to fix it with lists and whiteboards. When I was a kid I asked for a PDA before smart phones were a thing, but I just sort of forgot about it. Now I have piles of lists and tons of spreadsheets of lists that I don't really look at anymore. I haven't remembered to use my google calendar(that was going to fix all my problems) in months.

My real methods are to simplify and make habits. Just have fewer things to focus on and repeatable ways of remembering to focus on them. I'm not saying I'm that good at them either of them, but that seems like a solid way to get your shit together.

One thing I'm good at is asking myself 'Am I forgetting anything?' and visualizing what I did and the thing I'm about to do. I have left things behind, but I think I'm in the reasonable majority on this one now.

I try to meditate in the morning to put my mind in order before I start the day. If I could actually make a habit out of this, I think it would make a huge difference. The problem is I'm like allergic to habits. Doing the same thing the same way two days in a row seems nearly impossible, but I'm convinced that's one of the keys to this.

Automating really is the way to go. I used to miss credit card payments by like a day or two just because I forgot, but it's all on auto so I take myself out of the equation.

What is your business? How long have you been doing it?