She is in her 80’s. I mostly just explained WHY she would need one, and promised once she was done with the transition, things would be easier. Her old password method was a weathered old piece of paper with everything scribbled down on it, with lots of old pet names and other animals with random numbers attached.
Now she is very happy with being able to have all of her passwords ready either on her computer, phone, or iPad, and she feels a lot more secure with the long random passwords.
Very good, what you described is called an Infinitesimal, and it is a building block of Calculus.