Make duplicates of all keys. Bury a house key in a secret spot in the garden and carry a duplicate car key in your wallet, apart from your key ring. Practice preventive maintenance. Be prepared to wait. A paperback can make a wait in the post office almost pleasant.
Procrastination is stressful.
Don't put up with something that doesn't work right. Allow 15 minutes of extra time to get to appointments. Plan to arrive at the airport one hour before domestic departures. Relax your standards. The world will not end if the grass doesn't get mowed this weekend.