My mother is good at injections. I don’t know how she does it, but somehow she is able to give painless injections. When I inject I always feel pain instead my mother can do injections causing no damage.
Apparently she learned by doing experiments on mices, removing their skin and injecting on them. She was worried because mices suffered, so she tried to improve her skills. Now she has good injections skills even if she is not a nurse.