3. You can’t trust anyone
Happy people, while wary, generally trust those around them. They are open and friendly to others unless they have a reason not to. Seeing the good in others is a sign of a healthy mind. Meanwhile, unhappy people have trust issues and always assume that strangers and sometimes even friends cannot be trusted. Their behavior tends to shut doors on any potential connections they may have with others. As a result, they are often lonely and isolated.