I do a lot of yoga and pilates-type work with my preschoolers. Its really nice to learn to move and strengthen their bodies and it can really calm them down.
Pretending is the best way to do it. There are some ideas.
Have them lay on their back and tuck their knees in to become a BALL.
Then stretch their arms and legs out long like a BANANA.
Alternate between BALL and BANANA.
Lay on their bellies...reach their arms and legs out raising them off the floor like SUPERMAN.
Make sure to grab for STARS along the flight.
Roll over alternating BANANA and SUPERMAN.
Lay all the way down and reach their heads up like a SNAKE.
Coming up on their toes, roll into a standing BALL.
Pretend to grow up into a TREE....stretch out into BRANCHES....and shake their LEAVES.
Make a letter T with their arms.
Have the T fall from side to side.
I often make a game of saying different 'images' and having them hit each one.