You set yourself up to fail, you reset the goalposts when you are close to making things easier, you pull out an obscure memory to rationalise a decision, reaction or choice. You can use this big stick you punish yourself because you could not predict the outcome and use retrospect to shame yourself for not seeing it coming.
There is no glory in punishing yourself today for decisions you made in the past. The set of circumstances that existed in a past decision or situation do not exist and can never be replicated. If you grew up with shame or are susceptible to self criticism then you could be unconsciously using the past to stay in your comfort zone. The minute you become aware of the difference, even if you're not aware of the trigger, your comfort zone becomes your uncomfort zone and nothing will feel balanced until the bias is addressed. This video series explains the process in a fun and simple way that takes the power away from your critical self and gives it back to your creative self.