The popular saying is that “curiosity killed the cat”. But in humans curiosity can serve us well. When a person feels paranoia that others are watching or out to get him/her, that feeling tends to build on it’s own fear/anxiety. In order to counteract paranoia, I suggest finding a way to be curious about other people.
A person who is curious is not trapped. Mentally, there is an emphasis is on observing and learning, and that takes the place of paranoia. In other words, it is difficult to feel genuinely curious and paranoid at the same time.
So if I feel paranoid at the grocery store that everyone is looking at me, I could observe other people and ask myself such questions as, “Does their clothing match?”, “How old are that person’s shoes?”, or whether or not I think that person owns a pet, and what kind of pet I could picture them owning. If successful, my thought processes start to function with some logic based on observable reality.
If the curiosity angle isn’t working you can always try telling yourself, “They’re looking at me. So what? Some people are just nosy.”