There are many different styles to draw human figures, including stick figures, outline figures, silhouetted figures (black shapes against a light background) and balloon people.
You can use any drawing instrument you like, including pencil, pen, felt-tip pen, crayon, or whatever you remember you enjoyed using as a child.
Choose at least two styles and draw a few people in different poses. It may help you if you take up those poses yourself before drawing them. Or ask a friend or family member to pose for you.
Draw yourself in whichever style you prefer and in a pose that best represents how you feel about your invisible disease. You can also add colour if you want.