Smiling can work to counteract the effects of stress. By forcing ourselves to smile, we "trick" our body into believing that everything is good, thereby reducing stress.
Like a switch, smiling can actually change your mood. So put a smile on, even if you don't feel like it, and pretty soon you'll be smiling for real.
Self-talk, "I start & end each day with a smile. And throughout the day I conciously practice smiling and feeling good about myself."