I think every SEAL I’ve ever talked to said they did stuff in BUDS that they never thought they would be able to accomplish.

Sounds simple, but it takes a positive mental attitude to accomplish. You have to really want it, and use anything positive and/or negative to motivate yourself to complete that goal. When I was in AOCS, one look in the mirror after they shaved my head was enough to get me through at least a month of crap until my hair grew back. There was no freaking way I was going to quit and hit the street looking like that...lol