While most of the time, I remember my password, I know I could just snap and forget it right there at any point. Happened to me not once. And I'm in my 20s. Sometimes when I forget a password, I just start typing and muscle memory kicks in, sometimes it doesn't. I guess our brains are not optimized to store long random strings of characters. You could use a long sentence as your master password or do as I do:

Come up with a way to make up a long seemingly random password from a couple words. Then if/when you forget a password, just remember those words and reconstruct password from them.

• Don't use common dictionary words or anything from popular media, as it could be guessed by attackers.
• You can write down algorithm on a piece of paper and keep it somewhere safe.
• Words should be related but not directly:
  • two asteroid names - bad
  • asteroid name and it's greek translation - bad
  • real city name and city name from a book - good
  • two words that both start with S and end with T - good
• If you forget both words, you should be able to remember/look up at least one of them if you still remember how you came up with the word.