This is some great advice for a simple mindfulness tool that anyone can do from the book Eat, Pray, Love by Elizabeth Gilbert.
There has been a lot of practice and study in the power of smiling as seen in this article “The Power of the Smile in Our Meditation and Lives” by Steven Goodheart.
“Taken in the deep way intended, mindful smiling—and mindful is the key—can be very transformative. Here’s a short teaching by Thây on how he views the smile as integral to practice:
I always say that a smile can be a practice, a kind of yoga practice. Yoga of the mouth: you just smile even if you don’t feel joy and you’ll see after you smile that you’ll feel differently. Sometimes the mind takes the initiative and sometimes you have to allow the body to take the initiative.
Sometimes the spirit leads, and sometimes the body can lead. This is why when you have joy, you naturally smile. But sometimes you can allow the smile to go first. You try to smile and suddenly you feel that you don’t suffer that much any more. So don’t discriminate against the body. The body also can be a leader, not only the spirit.”