I believe that your ability to remember things is caused by a number of factors:
- How important those things are to you. If you find that you keep forgetting certain things, maybe you need to reexamine how important those things are to you. If you can remember the starting lineup of your favorite sports team from 20 years ago, but you forget relative's birthdays, I think you have your answer.
- Fatigue. My brain is much sharper when I'm well-rested than it is when I'm tired. I don't get much sleep as it stands, and things get worse if I have a bad night's sleep.
- How busy you are in general. If I have a lot of different things that I need to keep straight - deadlines at work, appointments, birthdays - there's a good chance I'm going to forget something relatively minor that I also need to remember. And, if there are multiple appointments for things in a close span of time, there's a chance that something important will get missed.
- How many things you need to remember right now. This sounds like the same thing as the previous one, but it's somewhat different. Here's an example: I want to get a drink from the refrigerator, so...
- If nothing gets in the way, then it's easy: I go downstairs, I get the drink, and I come back upstairs with the drink. This is the theory, at least, since I don't think this has ever happened.
- Almost invariably, something like this happens:
- As I get downstairs, my son starts talking to me about a video game he was playing, or some other thing that interests him.
- I see that there are empty boxes from a frozen dinner that someone didn't throw away. I don't want to just clean up someone else's mess for them, so I find who did it and ask them to please clean up after themselves (ironically, there's a connection between video games and pizza).
- When I open the refrigerator, I see that the light is burned out. Fortunately, I have a replacement, so I fix it.
- I also see that the diet Pepsi case is almost empty, so I get a new case so we won't have warm drinks.
- I see that this is the last case of diet Pepsi, so I either add that to the shopping list, or start a new list.
- I go back upstairs, and then realize...that I forgot to get the drink I went downstairs to get in the first place.
Now, combine all those factors, and the fact that I'm also not young seems to be a relatively minor point. At least, that's what I'm going to keep telling myself.