If you have a rear-view mirror, it really helps. I can see well enough ahead, and I have good periphial vision, but my aging neck is tired of craning over my left shoulder to see what's coming up behind.
Stay well clear of trucks. "Situational Awareness" could be intepreted to mean that the cyclist is aware that trucks are very heavy , wide, and have blind spots.
If you see a car pulling out from a parking space in front of a bar, you would be aware of the situation if you assume the driver has had a few drinks.
If you see a car with lots of dents and broken headlights, you should be aware that the driver has lots of accidents. Steer clear.
If you are riding down a city street and a ped raises his/her arm in front of you, be aware that he/she is hailing a cab and look over your shoulder to see the taxi cab.
Be aware of things that increase your risk of being hit. That is Situational Awareness.