This is relatable. How is it possible to think positively when you are surrounded by awful people and situations? Sometimes the individuals who are viewed as "negative" are not actually negative at all; they are simply in a bad disposition in reaction to other peoples bad behaviour. It is anger-inducing when a person who is being bullied - for example - acts unhappy, and yet they are the party that is labelled as negative rather than the bullies; surely it is the bullies who are negative? This could be applied to any situation where somebody is mistreated by another.
Contrariwise: not everybody who is viewed as "positive", is actually positive. It is an overused word; to some that are in the category, that like to preach about the concept, it means to just ignore the suffering of those around you. Everybody has their own definition of what it means to be positive, but to me the concept is about trying to be kind to others, because kindness is a "positive" trait - right?