The Mental Side: You need to understand that Boot Camps are built to BREAK you. It is a game.
If you take any of it personally, internalize any of it, let the yelling and the cursing get to you – you are going to break. You will fall out, you will ring the bell, you will DOR (Drop on Request).
My solution to this is to disassociate yourself with your situation; the pain, the stress, the exhaustion, the verbal abuse – put it all off as a TV show.
Maybe it is because I grew up in a shit of a household – but it has always been easy for me to dislodge from reality; to paint myself outside of the scene at hand.
You need to master that technique – while still being able to pay attention to what is happening around you in a heightened awareness. This is not New Age, psychic shaman stuff – it is the advanced training and skill set that if you go further into more elite cadres; you will NEED.