Great any time of the day - when you are stressed, overwhelmed, or just need to "let it go". This is also a breathing practice wonderful before bedtime, to engage the parasympathetic nervous system and help you prepare for sleep.
From the community
Modification to Sitting
I really liked the idea behind combing breathwork with movement here. I have a larger stomach and ended up doing this exercise from a seated position to allow my lungs enough room to fill.