On the first day of my medical house job in 1991, the registrar said to me: "You will quickly start to think you're irreplaceable. You're not. Remember that. If you get hit by a bus tomorrow, the consultant will look round and say 'Didn't we used to have a house officer? Get me another one!'"
You are replaceable at work, but you are NOT replaceable at home. A beautiful and poignant reflection that applies to all clinicians.