Also scary to do the "Lion" and "Lemon" facial exercises in the car as you tend to frighten those who are on the road with you.
Lion - open mouth as wide as possible - like you're roaring - open eyes as wide as you can, whilst rocking your head to and fro. Hold for 5 seconds, then go to Lemon - whole face puckered up tightly, eyes all squinty. Hold for 5, then back to Lion. Folks may think you're having an attack of some kind, but it helps to have a child in the car with you doing them too. They really do help relax all those muscles before singing.