It has taken me years to get in the frame of mind that I need to be healthier.  I am finally at that point and now my body is blocking me. My knee locks while walking, on the eliptical, on the recumbant bike and while swimming. This is uncomfortable but not altogether painful until the 50th time I have had to do it in 30 minutes.  Not to mention that today everytime I had to stop peddling and unlock my knee,the bike reset. Thankfully I had my tracker to tell me how much time I have spent on the bike.   I am not letting this get me down.  I will succeed even if I have to do it in minute increments. :)