I feel at the moment that I am on the right dose of Levo and my energy level was good. Two months ago I started jogging again, I paced myself and felt I was really making progress. But over the last couple of weeks I have found it a real struggle when I run and all my joints feel stiff. I don't think I overdid it and I am not sure if this is even connected to my under active thyroid. Has anyone else had a similar experience in trying to improve their fitness?