Back in the day (approx 12th-17th century), the practices of kriyas, bandhas, and mudras were very popular in the Hindu yoga texts for strengthening and purifying the nervous system. In a typical class, you will learn the different types of daily practices for intestinal health such as the abdominal contractions of uddiyana kriya and agni sara, energizing breath patterns, and others.
These practices are considered an essential foundation in Yoga for building energy and quieting your mind.
This class is 30 minutes long, and a bit of Yoga experience is useful for it. These practices will prime you for building internal strength!