oh, I don't know, eating a worm omelette as part of the classroom theory to survival training, running a few miles with a pine-pole during PT at Cranwell, annual dunking in the sea to practice your dinghy drills (usually in January!), inverted spinning in a Tucano, conduct after capture training, formation at night in cloud for the first time, caving, sailing across the North Sea, getting shot at by people who want to kill you very much because you have been asked to fly over their country.
The variety of the list is just a taster. The point is, the Service has no idea what is going to happen to you during the times that they ask you to put your life in danger (or if that time will ever come), but the system tries to prepare you for those moments to see if you (when the chips are down and people are really stressed), can cope and be part of the team instead of having to be supported by that team. I've seen other air forces do what we do, and all of us ask that you prove that you are worthy before we adopt you into the family. Do "interesting stuff" now to avoid disappointment. Air Training Corps will introduce you to unusual activities and see if the discipline side of it will suit you. If it doesn't, you can join venture scouts or something similar to pad out the CV, and more importantly become a leading member of the community which you choose to live in.