Not really 'fitness athletes' as such but all the below have incredible fitness:
I have great respect for Paula Radcliffe, the English marathon runner. She trains incredibly hard and is very disciplined and dedicated. I am pleased to see her doing so well in the marathon after her disappointments on the track, where she would lead a race from the front until the final lap until African runners pipped her to the medals.
I also admire Kelly Holmes who overcame years of serious injuries to win double gold at the Athens Olympics last year.
I am also a big fan of Merlene Ottey - into her mid-forties and still going strong. Bizarrely she now runs for Slovenia.
Ditto, Gail Devers, still very competitive despite having a quite serious disease I believe.
I like my track and field in case you hadn't noticed.