Waiting...

Over half of life has to be waiting. Even when occupying time with other tasks, you're still waiting for some ship to come in, which is needed for something else. Realistically, the amount is probably far more than half.

Waiting might be the whole of life. Wait to get old enough to do something. Wait until you have enough resources to do something else. Wait, wait, wait... Ultimately, and perhaps a little morose to contemplate, we're waiting for death.