Any tips before going into SFAS for the green berets?

Answer 1

Two things to remember;
1. They break you physically and emotionally in order to reform you into what they want-so play the game, become what they want but still keep a small part inside of you that is untouchable, that will keep you sane (as possible).
2. Do NOT think you are the world's toughest person-there is always someone else who on their best day can whup you on your worst, and that day might be any time.
Keep these in mind, you will come through just fine.

Answer 2

Hopefully, you've been working out, and running to get yourself in the absolute best possible physical condition you can be in. That will assist you in the physical endurance part. However, what causes most folks to fail selection is the mental endurance piece:
As others have said, the pressure will be on you to quit. The idea is to see what you're willing to do to complete the mission. You also need to be there for the right reasons; this is something you want to do, and it's not for cool-points, bragging rights etc. If so, you'll be one of the 80% who won't finish.
Good luck, stay focused. (Oh yeah, "green beret" is a hat. You'll be better off by referring to USA Special Forces members as "Special Operators". Just a friendly tip :) )

Answer 3

Just keep telling yourself "I'll pass out before I'll quit. The only way I'll quit is if they have to carry me out on a stretcher."