Relaxation is a key benefit of the yoga practice and can be experienced by anyone quite easily. Lying down, tuck your tailbone under so that your sacrum is fully supported on the ground. Take the feet at least hips width apart, perhaps wider.
Allow your knees to roll inwards so that they touch at the centerline of the body. Take your hands to your abdomen and close your eyes. This is also known as "constructive rest" position. It helps release the back muscles, psoas, and legs, but more importantly it gives your mind a chance to wind down.
Follow your inhalation and exhalation, counting backwards from ten. Allow the breath to deepen, and if possible, use your full lung capacity by activating your diaphragm. If you are very relaxed the breath will be deep in your belly—but do not force this to happen.
Take this simple relaxation exercise anytime you feel stressed, at the end of the day, first thing in the morning, or whenever you need a few moments of peace.