Spontaneously? Almost never. Once in third grade when my teacher had a grand mal seizure during a lesson and conked his head on the blackboard. I got a pair of box turtles from my parents as a reward for having the presence of mind to go for the school nurse while the rest of the class was still panicking and milling in circles. They lived for ten years after that, not the 50+ I had hoped for, but they were probably wild-caught as adults, so that wasn't so bad. One of them might still be alive out in the wild somewhere -- he didn't come up from hibernation one year and I don't know if he died or escaped.

Other than that, a lot of planning goes into "spontaneous" moments like that for me. I spent 8 years volunteering intensively for an animal rescue group, including 3 years on the BoD. Went on a lot of cruelty calls. Called a lot of emergency vets. Occasionally grabbed a panicking horse before it hurt someone. Now I'm a victim advocate. I spend most on-call nights hoping the pager doesn't go off because I really don't want to be bothered in the moment, but when it does I always wind up glad that I was called, because I get to really help people.