Genghis mentions thinking ahead of the aircraft. Absolutely right.
I would take it a step further. If you are thinking ahead of the aircraft, you then develop the capacity to think outside the aircraft. To me, SA is about understanding the overarching environment, of which you and your aircraft are a small part. SA encompasses the ability to accurately and rapidly assess or even predict the outcome of your actions and those of others. It come with practice, experience, natural aptitude, attitude and mental capacity.