Get in shape physically. GOOD SHAPE.
If you don't already know, learn how to say SIR!
Be psychologically prepared to be treated like sh!t.
Be aware that everything they say and do, no matter how much you hate it, is for your own good, and to keep you alive in battle.
Get yourself "psyched up" that passing isn't good enough. Only being number one is good enough. That mindset will serve you well throughout life.
Be not just prepared, but willing and anxious
to work your ass off 14-16 hours per day for a couple of months.
GOOD LUCK AND GOD BLESS YOU!!!!