I find this an oddly positive question. (As in, "Learn from your failures. Celebrate the bravery of your attempt.")

For me it's an hour-by-hour thing. "I'd hoped to get more done than I did. Maybe the next hour will be better..."

Breaking into FAANG. I just went through a serious set of interviews, did everything right, and everything seemed positive, but alas was beat out by one or more competing candidates.

properly marketing doc2exam.com

someone said it's solid but I've already spent so much on other projectcs' marketing that I just don't have the energy to spend more and again see it with 0 users

plus, I have another, easier to monetize project, and trying to move fast with that one

Getting to bed an hour early, in preparation for the start of Daylight Savings time.

Marriage