With my rescue diver cert, it changed how I dive. Specifically, I really watch others. ..on shore, on the boat, prepping their gear, how they enter, how they dive. I'm not trying to be a SCUBA cop, I just offer a little friendly advice where applicable. I've certainly been given similar friendly advice. Dive accidents occur as combinations of small issues stack. So a little advice can prevent that from happening.
I dive with my son alot (he's 14) and we are constantly discussing best practices, drills and potential problems. Then practicing. Last week I wrapped him in my smb rope and tied a fin, arm, mask, first stage reg and required him to get free. He methodically and slowly did so. Calmly.Then he did it to me. Then we discuss. It builds him into a stronger, more confident and comfortable diver.
PS. Yesterday I dove a high mountain lake (6600 FT). Turned out it was only 10 ft deep, but very new experience for me. Cooooold water, full wet suit, gloves, hoodie, etc etc. I learned a lot from the dive. I logged it. Totally new experience for me.