Injuries and illnesses are all part of being a professional athlete and the severity of an injury varies from sport to sport. You need to learn what is a niggle and what needs attention and rest. Tennis players nearly always have some pain in their body when they are competing, from blisters to a pulled muscle, but as long as they know how to deal with it there is no need to panic. Of course if an injury is causing too much discomfort or getting worse, you will do more damage by continuing to compete so you must reluctantly rest and re hab. You learn more and more about your own unique body as you mature and actually you learn from each injury you recover from.
Girls have an extra guaranteed dose of pain and illness every month. Yep, we do and it makes you feel a million miles away from a professional athlete.