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