Your Chest and Stomach:
Take a deep breath and tense all of the muscles of your chest and stomach. Hold for a count of 10 then breath out and relax to a count of 20. Repeat.
Your Shoulders:
Try to touch your ears with your shoulders to tense the muscles of your shoulders. Squeeze the muscles for a count of 10 then relax for a count of 20. Repeat.
Stretch your upper arms backwards, as if you were trying to touch your shoulder blades together. Hold for a count of 10 then relax for a count of 20. Repeat.
