This meditation is a form of Transcendental Meditation, which is a seated meditation with a short mantra to repeat and act as a guide for your thoughts. The mantra is "Sa Ta Na Ma," which translates from Sanskrit as "pure essence," "identity," and "truth." The syllables individually translate as Sa birth/beginning, Ta infinity/existence, Na death/change, and Ma rebirth/regeneration. The mantra is meant to remind you of these themes throughout this meditation.
Sa Ta Na Ma, the Kundalini meditation, is a reflection on one's core values; it can be an excellent daily reflection to gather your thoughts on existence.
To start this meditation, find a meditative position seated with your back comfortably straight, and find a rhythm of breathing with the whole of your lungs for about five-seconds a breath. There's no need to keep track, but find a deep and relaxed rate of breathing. After a few minutes, repeat the mantra Sa Ta Na Ma every time you exhale.
While taking deep, relaxed breaths and including the mantra when you exhale, release any tensions in your body and mind. Note any thoughts that occur and then do your best to brush them aside for now. When your thoughts inevitably return to why you're repeating the mantra- Sa Ta Na Ma- remember the meaning behind the words. This will orient your thoughts towards the scope of this meditation.
If you experience a flurry of more trivial thoughts, allow yourself more time, and you will eventually see this flurry in greater perspective and be able to quiet it, or at least give it its place in your mental space. More thoughts than what seems like usual may flood your mind when trying to focus. Maintaining focus on a mantra meditation can sometimes be like holding a strong fish, in that your mind may try to throw itself to escape the themes the mantra guides you towards. It can take time to relax into letting the mantra guide you past the initial frustrations of a busy mind.
Over time, the theme of this mantra- conception, existence, change, and regeneration- will lend itself to your typical stream of thought. New perspectives and insights will open to simply from orienting your thoughts towards the more profound scope of these themes. This is a great meditation to experience a coherent sense of self and purpose. It's also helpful for seeing past self-imposed restrictions and blind-spots we all harbor within our identities, whether these present themselves in daily life, within a particular endeavor, or in an impending problem such as existing!
Previous Introductions to Various Meditations:
Why Practice Meditation?
Dark Night of the Soul
Exposure to Fear
Tibetan Light Meditation