This happens so frequently, it's embarrassing. More often than not, there won't be any lapse of time between what I was just thinking about doing and the moment when I realize I've completely forgotten it.
Thankfully, I've gotten better at remembering things that are important, like when I have to go to work and what I need to get at the store, but I'm still crap with dates and days of the week.
Every now and then, I'll go out of my way to buy a planner, usually something nice so that I'll actually feel compelled to use it. I'll fill it up religiously for the first few months and then promptly lose it.
