How do i improve my awareness of my surroundings?

[Aasd S]

So i was walking out of best buy thinking... How can Jet lee or any martial arts person have such a keen sense of who is around them and how to react. They basically act off pure instinct to do something, and yet it is so much better than if it were planned out. I was just wondering how i can improve that, sort of guess how something might happen or at least be able to tell where people are in my peripheral vision/around me. THANKS!