Health, a light body, freedom from cravings, a glowing skin, sonorous voice, fragrance of body: these signs indicate progress in the practice of meditation.
The Shvetashvatara Upanishad is one of the older, "primary" Upanishads. It is associated with the Black Yajurveda. It figures as number 14 in the Muktika canon of 108 Upanishads. Adi Shankara has called it the "Mantra Upanishad" of the Vedic Shvetashvatara school.