You *do* something for a 2 year old because he can’t do it himself. You *help* a 5 year old with something because you want him to see and learn, and may be because you want him to do it himself from next time onwards. You *help* a 50 year old with something because you want the old man to not take much strain, and not because the old man can’t do it himself. You *do* something for a 65 year old because it is too hard or not-possible for them to do it themselves. Now, there is a difference between *helping someone with something* and *doing something for someone*...also, the age is just a number, it literally is.
If you make an 8 year old sit on your lap, he is not going to like it coz he is old enough and he doesn't need your lap/support coz that makes him feel uncomfortable. Similarly, if you do everything for a 50 year old, he might not like it and feel like you treat him as if he is not good to do anything himself, he might feel like he is too old, but in reality he isn't old enough for you to do everything for him.
Gauge the need: some people need your help, some want you to do something for them. You gotta watch out for that coz you might make them feel that they aren't old enough or they are too old already.
Old enough
