Breathing is one of the most effective techniques to manage stress. One very simple yet powerful technique to relieve stress is 1-2 breathing. In this, the time to exhale is twice that of the time to inhale. So if you take 4 counts to exhale, the counts to exhale would be 8. Please do not force. Initially it'll difficult to double the time for exhalation, but after some practice, it'll be easier. Just 5-10 minutes of this practice can bring profound relaxation in you.