There is a simple but powerful self-healing meditation that you can do whenever you feel the need to boost your immune system. It is particularly effective if used when you feel the first symptoms of an illness, but it also works with illnesses that are already entrenched if you use it at frequent intervals and with an intense focus. It will also counteract any disruption of your energy field by some form of negativity. However, it is not a substitute for the moment-to-moment practice of being in the body; otherwise, its effect will only be temporary.
Here it is.
When you are unoccupied for a few minutes, and especially last thing at night before falling asleep and first thing in the morning before getting up, "flood" your body with consciousness. Close your eyes and lie flat on your back. Choose different parts of your body to focus your attention on briefly at first: hands, feet, arms, legs, abdomen, chest, head, and so on. Feel the life energy inside those parts as intensely as you can. Stay with each part for fifteen seconds or so. Then let your attention run through the body like a wave a few times, from feet to head and back again. This need only take a minute or so. After that, feel the inner body in its totality, as a single field of energy. Hold that feeling for a few minutes. Be intensely present during that time, present in every cell of your body. Don't be concerned if the mind occasionally succeeds in drawing your attention out of the body and you lose yourself in some thought. As soon as you notice that this has happened, just return your attention to the inner body.
If at any time you are finding it hard to get in touch with the inner body, it is usually easier to focus on your breathing first. Conscious breathing, which is a powerful meditation in its own right, will gradually put you in touch with the body. Follow the breath with your attention as it moves in and out of your body. Breathe into the body and feel your abdomen expanding and contracting slightly with each inhalation and exhalation. If you find it easy to visualize, close your eyes and see yourself surrounded by light or immersed in a luminous substance—a sea of consciousness. Then breathe in that light. Feel that luminous substance filling up your body and making it luminous also. Then gradually focus more on the feeling. You are now in your body. Don't get attached to any visual image.