Keep the lungs breathing fully to support your immune system. Cardiovascular activity and yogic breathing exercises are helpful in keeping your lungs moving fully so that toxins are released completely and the lungs are able to absorb fresh air.
We usually do not use our complete lung capacity which allows residual air at the bottom or the lungs to be stagnant. Take time to fully expel residual air and take in fresh. Shallow breathing and the inhalation of toxins prevent us from releasing toxins with our exhalation. These also limit how much clean air and energy, or qi, we can breathe in from our environment. This diminishes our immunity.