Cecelia Waggoner has been blessed with being around long enough to see the effects herself. There are people in our neck of the wood who are getting nursing care because of what she did forty years ago.
For most of the rest of us, we don’t get to see it ourselves, but it’s there even with something as simple as being a parent. (By parent I mean someone who raises their kids as opposed to just throwing food to them every once in awhile like you were feeding a squirrel.)
To keep the math easy, let’s say you have two kids and that they have two kids when they are 25 and this continues from generation to generation. This will go out as 2, 4, 8, and so on. Eventually there is a generation of more than 1000 people who owe their existence to you, but you’d have to live to be 200 to see it. If you have more kids, it’ll happen quicker. That’s just a mathematical fact.
I just use parenting as an example. Teaching also works, and I don’t limit the act of teaching to those who are in the classroom. My daddy was a truck driver and I still hear from people who worked with him and were affected by the way he did things and things he said: “You don’t have to drive so d**n fast if you don’t spend all your time drinking coffee with some pretty waitress.” It all goes out in a ripple multiplying as it goes.
It is very rare that anyone gets to see the effect they’ve had. It takes more than the standard threescore and ten for it to play out and most of the time it’s too diffuse to be seen easily. Think about the person who taught you to write. You use that everyday. Think about the people who’ve gone out of their way to help you; did you even know they were doing it? Did they live to know how much they helped you?