The technique is called Anapana, it is the first subject of meditation expounded upon by the Buddha. Anapana is defined as the observation of the natural breath. It will help you focus your mind and prevent uncontrolled stream of thoughts from creating physiological stress. Health begins with self-awareness.
The best time to practice is in the stillness of the morning, in the delicate place of being awake, but not yet sucked into the chaos of the day. A goal of 10 minutes per day is a good start. Make sure to use and trust a timer to keep track of the time, no peeking. If you can only manage 5 minutes do not be discouraged, what matters most is that you are consistently trying. If you feel so inclined practice an additional 10 minutes at the end of your day, as it will leave you calm and peaceful as you head into sleep.
Sit somewhere quite and relaxing, in a comfortable position where you can maintain a straight back and neck. If you are capable, crossed legged on a cushion is preferable.
Focus your attention on the sensation that occurs on the area below the nostrils and above the upper lip associated with breathing through your nose. Remain constantly aware of the incoming and outgoing breaths. Observe the sensation, do not count your breaths, or control your breathing, simply observe the sensations as the air naturally moves in and out. It is not necessary to breathe deep or shallow, simply breath and observe. Your thoughts will continue to bombard you. Stay focused and forgiving as you return your attention to the sensation of your breath. Do not allow yourself to become frustrated with your mind’s wandering and lack of focus, it is the untrained nature of the mind. Stay alert, be aware of the reality of this moment as it exists, and do not attach thought or meaning to it, simply let it rise and pass away with acceptance and equanimity, from moment to moment. This is the true reality of life; change and impermanence. Awareness and equanimity are the two wings of the bird needed to fly.
~Seek peace, and contentment and happiness~