Memento mori (remember that you [have to] die)

Meditate on the fact that we are not immortal.
Ask yourself daily: “Have you given your best at work? Have you expressed your love for your family and loved ones today? Did you do anything that would benefit society? Have you made ethical decisions today?

During the day, or at the end of it, take time to reflect on your bad and good actions and decisions.
If it were the last day, would you be satisfied with the result? What would you do differently? Would you change the way you interacted with others? How can you use this information to make better decisions in the future? Act on your thoughts.