What exercises can actors and others do to encourage relaxation?

Why do you want to encourage relaxation? Exercising serves two purposes, to relieve stress and to wash garbage away from the walls of arteries. To wash garbage off artery walls requires 30 minutes of movement. To relieve stress requires constantly using your mind in the here and now. A relaxing exercise is one that avoids competition and conflict. Yoga or aerobics or any exercise where your mind has to be with the here and now and can not wander is relaxing. You can follow that up with a 30 minute walk or a 15 mile bike ride or anything else for your cardiovascular workout.