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:

[1] 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.

I heard a yogi very interesting lecture, in which he spoke about the following exercise:

1. Breathe in deeply but slowly. Imagine how the air you breathe brings life into your body.
2. Breathe out slowly. Imagine how you release the air to make room for the next cycle of breath, and at the same time offering the world your inner light.

Simply wonderful. Try it, it really made me feel great! 

Yogic Breathing practice is routinely exercised.

Yogic Breathing is called Pranayam (breath control), which formed from "Prana" - life force or energy (also refers to the breath); and "Ayam" - meaning control or regulation.

I found an interesting article about it in the literature:

Tiwari, N., & Baldwin, D. S. (2012). Yogic breathing techniques in the management of anxiety and depression: Systematic review of evidence of efficacy and presumed mechanism of action. Mind & Brain, 3(1)

I once had a headache for days, and only when I began to notice the tension and stress that affect my breathing, noticing that I breathe badly, I started to pay attention and this horrible headache went away!