One hand for oneself and one for the ship.
Prov. When you are on a ship, always use one hand to steady yourself, and one to work; likewise, always put some effort into safeguarding yourself as well as into working. The old sailor chastised us for forgetting to hold onto something during the rough weather. "One hand for yourself and one for the ship," he bellowed. This company expects you to work hard, but not so hard that you hurt yourself. One hand for yourself and one for the ship.