Dedication, integrity, intelligence, tenacity, self-awareness, situational awareness, trust of your teammates (giving and receiving), honor, and there is a je ne c'est quoi inherent in the breed, those who are or have been in any Special Operations unit are aware of this - and still can't describe it.
Success in the SOF world is keeping and maintaining all of the above while honing the trainable skills needed to get the job done, loving the suck and hating the suck.