As we age, our immune systems become less able to respond. We have fewer immune cells and inflammation increases. Stress can further weaken the immune system. If we are of a certain age, there is a higher dose flu shot that helps compensate for this fact. But what about other issues we need our immune system for, such as healing, reducing inflammation, or illnesses that may not have a vaccine? There is evidence that practicing yoga may help us boost our immune systems, reduce inflammation, as well as reduce stress.