Focus on one unconscious behavior: breathing.
Our daily life can be so stressed, that surprisingly we simply forget to properly breath. Close your eyes for just one minute and pay attention to your facial expression and muscles. Relax them, and then slowly breathe in and out. Repeat it for few times, and you’ll see that not only you feel better, maybe more relaxed, but you breathe better.
Research even shows that breathing disorders may be connected with anxiety and depression. A reference example:
 Kunik, M. E., Azzam, P. N., Souchek, J., Cully, J. A., & al, e. (2007). A practical screening tool for anxiety and depression in patients with chronic breathing disorders. Psychosomatics, 48(1), 16-21.