Yes, www.goanimal.com is a good link.  There is a lot of thought and
learning gone into it.  (Wish I lived in their area!)  See especially the
discussion at
 http://www.goanimal.com/panorama/what_is_fitness/what_is.htm

which distinguishes clearly between "fitness" as we use the term loosely in
terms of exercise and physical well-being and the meaning of "fitness" in
the much narrower Darwinian sense.  VERY helpful.

Keith Thomas