I had a total knee replacement in Dec. of 2008 and it was the best thing I ever did!! I had to pedal an exercise bike as part of my therapy back when it was healing. I can even dance now...it is amazing!!! The only thing I don't do is run. Went to the ocean a few weeks ago with oldest and family; I was even able to walk along the shore with my feet sinking in the sand. Yes, it made me a little tired; but I WAS able to do it. You should have been good after 6 months; but I do understand there are some individuals who have not had the success I have had. Fear is a great enemy of adults....that is why children can do so much; they are fearless!! Hang in there, and I pray you will find the courage to do it.