It may help to visualize yourself filling your stomach with air, as it if is a balloon.
Focus on breathing horizontally, rather than vertically. Breathing horizontally means that your diaphragm and abdoment should move outward instead of the usual up-and-down movement that accompanies shallower breathing.
Repeat this exercise once or twice daily.
You should not only feel your body expanding at the front, where your hands are, but also at the sides and back.
