[header] How to look happy [title] Take a deep breath and let your muscles relax. [step] Remind yourself to let the tension out of your muscles with a deep breath. Just relax, letting the small muscles in your face, neck and shoulders unclench. 
Are there any parts of your body you have curled or tensed nervously? Let them go. This physical tension is picked up by other people, even unconsciously, and tells them you are stressed or unhappy.