When drunk you start to have doubts and regrets, you decide you wont drink so much again, or you will start dieting/exercising these resolutions feel like new years until you wake up the next day and either have forgotten about them or give up on them.
Bill: Man I'm totally getting up early tomorrow and hitting the gym!
Next day Bill wakes up at noon and eats leftover pizza and watches TV and realizes hes made yet another drunk resolution