Overgeneralisation occurs when we use information from one single isolated event and assume that things will always be that way. It can be detrimental especially when we hold onto one negative experience in the past, and expecting things to always be that same way. We are also subjected to confirmation bias (where we look out for info that confirms our belief) so that the negative expectation becomes a self-fulfilling prophecy. 

Break the cycle of negative thinking by becoming aware of the 'mental goggles' that you are wearing.