Start them young, build habits. Peer pressure will have less influence if it is a well established habit.

There is so much individual variation in people. One of my sons needs "encouragement" in this regard, the other one is like me and will EDC the kitchen sink if he has the room in his bag.

Mine will EDC at a minimum their phone (and no questions asked if they call for help for anything), money, flashlight, a patrol officer's first aid kit (pocket size trauma kit for the individual), and a waterproof/windproof jacket. This is for normal school days.

When traveling they will have the normal 10 essentials, minus the knife for certain circumstances. In those situations, they will have a pocket saw and EMT shears. I also add a military strobe light, poncho and a survival kit that I built. All in all, it is still less than 10 pounds.