It’s nothing fancy, just a little one I got at an office supply store about ten years ago. At one point I tried using a larger one, but that one was so big that it was a pain to carry with me and I left it at home, and I wound up not using it because it was always where I was not.
I started using a planner because I was losing things. Not physical things like my shoes or my keys, but temporal things like doctor’s appointments and meetings with the kids’ teachers. I’ve never been a terribly organized person, but when I was the only person I had to keep track of I could manage all right. When I suddenly had to keep track of things for two other people as well, I found that my mental juggling skills just weren’t up to the job.
I had to teach myself to use the thing. Like any other habit, it took a while to establish; at first I would forget to write things in and thus would still lose things. Eventually it became routine to write things in the planner immediately, and check the thing daily to see what was coming up. I don’t have to try and store the details in my easily-overwhelmed little mind. It’s like having an external USB drive for my brain. My friends and family are all well-versed in the use of my cerebral extension; whenever they tell me about some event or information, they’ll tell me “put it in your planner” if it’s something important that must not be forgotten.
I’m quite fond of my little planner. It gives me the illusion that I know what the hell is going on.