It is said even if you accumulate virtue as big as a forest, you could simply burn it all up with the fire of anger. Always remember you are a Qigong practitioner. Even if you have every reason to be angry, do not let your anger exceed 3 minutes. When you really have to become angry, try not to be angry in your heart. If you cannot control your anger, stop Qigong practice for some time.
Anger pollutes the whole body and has very harmful effects on the body afterward.
It takes long time for the body to recover. Anger damages subtle energy channels. It is said when one practises regularly, one develops or opens certain energy channels in one's body, especially in the brain. Anger closes or damages these subtle channels. Anger blinds the mind.