I often struggle with feeling incredibly guilty when I miss a workout or don't make adequate time for a given task in my day. When we attempt to live our life by this motto, we can avoid that feeling of dread by acknowledging that we met our goals for the day OR that our goals were not as important as whatever else took up our time for the day.
Whatever you fill your day with, let it be something you will not regret later! Have a day full of NO REGRETS! :)