I have been on 150mg of levo and felt ok, but started walking/jogging for 30 minutes 3/x/week (mostly walking). After 4 weeks was exhausted, so upped my meds to 175. I have exercised before (pre-hypo) so I know how I should feel. I still didn't have the umph to keep doing it so took 200mg every other day. My legs were bothering me by this time (never had before and have good gym shoes) and had terrible restless legs on the evenings and then in bed. So stopped all that and went back to 150mg.
I'm now taking 1 grain of Nature-Throid and 50mg levo. I'm lightheaded for several hours after taking it and am dragging a bit. Have been on the 1 grain for 1 week. I eventually want to get the meds and dosage right so I can go back to jogging without any side affects.