The short-term benefits of meditation are more than mere peace of mind, because our physical health as well depends to a great extent upon our state of mind. Therefore, if you cultivate a state of mental contentment and peace, then you will tend not to become ill, and you will tend to heal easily if you do become sick.
The reason for this is that one of the primary conditions that brings about illness is mental agitation, which produces a corresponding agitation or disturbance of the channels and energies within the body.
—Thrangu Rinpoche
Great Middle Way 