Druids work with energy, starting with one's own energy body, that is to say, the field of energy that surrounds one's physical body.
You can learn to feel your body energy by rubbing your palms together briskly, then holding your hands, palms facing, just a few inches apart. You will feel a tangible energy field between your palms. You can continue to feel this energy as you move your hands farther and farther apart. Having practiced this, I can now feel the energy field no matter how far apart I place my hands, even without the initial brisk rubbing of palms.
You can also become aware of your full energy body by focusing on each part of the body in turn, starting with the feet and moving the energy, bit by bit, up to the head. With practice, once the energy moves from feet to head, you can enjoy the feeling of your whole body pulsing with energy. The sensation is a spacious one, as though your body extends outward into an energy field, or as though you are composed not only of your ordinary body but also of an energy body surrounding it.
The idea in Druidry is that this energy body is very real. Working with the energy body simply by becoming aware of it and experiencing it in this way is healing. It is also a good way to open and develop the chakra energy centers at a natural pace.