What sports does she like? Does she enjoy playing sports or just watching sports? What kind of fun things does she like to do with her friends (you need to be more specific).
Some quick ideas:
A pedometer and a stainless steel water bottle
A gift certificate to her favorite restaurant or some movie tickets
Hiking/walking sticks like these
A nice fleece hat and a matching sweatshirt or hoodie for walking outside in the cold weather
A portable seat (to take to sporting events) like this or a seat cushion like this