After becoming familiar with the 3 stages of the breath, we practice a ratio of 4:2:4:2 - breathing in for 4, holding for 2, breathing out for 4, holding for 2. This can be called Visamavriti pranayama, where we practice the breath as "uneven" to mildly stimulate the nervous system. Completing the practice with the 3 stages of breath again and a short relaxation. Practice this after your strong asana or just by itself to balance and restore.