The biggest health threat in the modern world is stress. For many people a hectic job and unhealthy eating can lead to a mountain of stress. However yoga will teach you to reflect inwards on the thoughts that cause stress and be in control of your body, mind, and spirit. The body, mind, and spirit are all connected. The practice of yoga is centered around making sure all three aspects are harmonious. Even if one aspect is not functioning, your life will not be well balanced and this will lead to unhappiness or ill health.
There are two types of yogic asanas (postures): asanas for meditation and asanas for strength/flexibility. Both the meditative asanas and physical asanas are equally as important. A good meditative asana should be comfortable and stable and ensure your head, neck, and back are aligned. If the body is uncomfortable, it makes the mind distracted and agitated. The physical asanas are practiced to keep your body healthy by strengthening your muscles and keeping your body flexible.
I believe yoga can and should be practiced by people of all ages and from all walks of life. Yoga is a spiritual quest. Therefore, along the way you will gain health, happiness, and tranquility.