Believing that people are out to cheat you causes unneeded stress and anxiety. If you are constantly worried that a cashier will shortchange you or that a coworker will try to steal the spotlight or that an acquaintance is talking about you behind your back, you won’t be happy. The more you perceive that you can trust others, the happier you’ll be. Of course, you shouldn’t blindly trust people you don’t know, but go in with a positive attitude and give others the benefit of the doubt.