What happens during highly emotional states especially low energy emotional states like anger, frustration, pain, embarrassment, shame, guilt, regret, punishment is that we are in a highly emotional state to fix it. So we take a snapshot in our mind for our future reference to protect ourselves from the same kind of experience. It is a protective mechanism and during these negative energy states your brain makes certain conclusions and those conclusions or inferences that you make out of the event saves very strongly in the brain memory. Unfortunately these conclusions are most likely are not rational and logical. They are made in a hurry to satisfy our ego in the state of fear and hence they lack big picture and objective evaluation.
Here is the reason why we are afraid of the negative consequences than being inspired by the positive outcomes of a any pursuit in life. Let us take the example of giving a speech in front of hundreds of audience. It is highly likely that you would give a good speech and present yourself well on stage if you put in the hard work, practice and if you have done enough research on the topic. Even though we imagine the audience is applauding for our performance our dopaminergic (reward) centres of the brain do not get activated for hypothetical rewards. But at the same time your flight or fight centre of the brain which is amygdala would sure get activated the moment you imagine you fumbling on the stage or blacking out or people booing you or laughing at you. So our brain has high affinity towards negative events of life even though imaginary. It is an ancient survival and protection mechanism inbuilt in our brain.
So hypothetical positive experience is will not trigger and activate the reward centres of the brain but negative hypothetical events will trigger negative emotions in our brain and survival mechanisms in our brain. That is the reason why we suffer more in our imagination than in reality.
Do read the Disclaimer