Stop what you're doing

Take 2 deep breath and count to 8 both times
Tell yourself to let go of all control
Tell yourself you no longer have control
Tell yourself it's okay to let go, you're open to receive whatever is coming your way
Give up
Give in
Give away 

This is the process I'm trying to teach myself to do every time I go on stage, before entering a set or audition or when I'm about to start digging in a characters life. It helps a lot. Just stop what you're doing take 2 minutes to do this and reconnect your mind to the heart and the hear and now.