Suppose there was a knock on your door at 11 pm, and there were two policemen standing there, and they ask, "are you so-and-so?" Do you think you might be feeling some stress in that moment? Some fear and anxiety? But what if at 10 pm you had received a phone call: “Somebody found a wallet with your driver’s license and some money. We’re going to have a squad car come by to return it to you.” If that were the situation, you would probably have no fear, no anxiety, and therefore no stress.
So, stress is not caused by the situation itself – in this case policemen knocking on your door late at night. Instead, stress has to do with NEGATIVE EMOTIONAL PRESSURE due to our PERCEPTION of there being something adverse or threatening to us in that situation.