Yoga is an exercise from ancient India that is used worldwide that works on physical, mental, and spiritual well-being where you detach your mind and let the flow of energy go through you. This results in increasing your energy and mood improvement.
Although Yoga is not technically a meditation many people do it in a meditative state and it creates a positive state of mind and increases the life force (Chi or Qi) within you.
While doing the different poses helps you keep your focus for a meditative state and focuses on ujjayi breathing where you fill your lungs with air and exhale through your nose.