“a hundred days of sermonizing, one fart” → a metaphor for how something that one has put great effort into can come to nothing after even a slight mistake, much as a hundred days of serious spiritual study can be lost to the winds

a word once spoken is hard to catch even with a four-horse carriage; a word once spoken cannot be undone

(literally) plan your day during the morning, plan your year during New Year's / early planning is the key to success