Do you let people into your safety circle without noticing them? Your safety circle really comes into play in parking lots or other public areas. Think of a 21 foot circle around you. The average person can close that distance in 2-3 seconds. That doesn’t give you much time to recognize a threat and respond.
This doesn’t mean you don’t let anyone into your safety circle, it simply means if someone enters that 21 foot zone, you need to be aware. Most people will be passing through on their way to complete their own business. You can recognize and catalog them mentally as no threat. Then…there may be one that just makes you feel “off”. That is your instinct. Trust it! Watch the person, tell them to stay back, be prepared to respond.