What works for me is abdominal breathing (for example 10-20 minutes just laying on my back 1 hand on the belly and the other one on the chest and breathing only with the diaphragm - hand on belly going up and down) This kind of breathing is healthy for all the body. But I found out it makes me more fluent when I do it every day and when I try to make it a habit to breathe like that all the day..