Yoga is such an effective practice for anxious children because it soothes their mind which, in turn, soothes the body’s stress response.
Yoga can alleviate the feelings of anxiety and stress in the mind, which gives the body the signal to slow down all the physiological arousals. That means the calmed-down mind translates to a calmed-down breathing pattern, a slower heart rate and lower blood pressure.
https://www.heysigmund.com/anxiety-in-children-things-kids-say-that-could-mean-im-anxious/