Progressive Muscle Relaxation (PMR), taught for almost 100 years for stress and anxiety reduction, involves alternately tensing and then relaxing the muscles (one muscle group at a time).
You can do PMR sitting or lying down, with eyes closed. Muscles are tensed (for about 10 seconds) and relaxed (for about 20 seconds) sequentially through various parts of the body. PMR takes as little as 15 minutes once you learn the technique.
Try it tonight with these Progressive Muscle Relaxation Step-by-Step Instructions.