One of the things we do really, really well in scuba instruction is make divers terrified of getting DCS. By that, I mean we probably do it a bit too well. If you have been on ScubaBoard for a while, you will have seen countless threads in which people are afraid that they got DCS on a really mild dive on which there was next to no possibility whatsoever.
I see some instructors that scare me when talking about DCS! When I teach I make and repeat several very key points.
1) I emphasize that DCS is fairly rare if you follow the safe diving practices we talk about
2) I go through the physics and physiology and explain what DCS is, how/why it happens and how we as safe divers mitigate that risk
3) I go through the first aid response to suspected DCS
4) I repeat #1
5) we go thru ascent rules, safety stops, dive computers
I don't do scary. I don't do exploding lungs. I do emphasize safe diving. it's that easy.