The philosophy behind pranayama or "breathwork" is that by controlling one's breath, one can settle the fluctuations of the mind. For example, to simply focus on counting 10 steady breaths in a row, you must part with your other thoughts. In short, it's the breath (not the booty, or the biceps) that drives an asana practice. On its own, the practice of pranayama is a tool that can help you calm down, recharge, or refocus wherever you are.
Anuloma pranayama is a highly effective exercise, during which you alternatively block and release one nostril and then the other. The result is a calm sensation in the body and mind. While slightly awkward at first, this breathing practice is not difficult. Of course, having fresh air around you and being within nature while doing pranayama is a great treat; however, you can just as easily do this work at home or before yoga class, while sitting on your mat.
Notice how a dedication to your own breathing (even for a short period of time) leads to calmness, peace, and clarity within the rest of your being.