I am a 69 yr old female. I had a thyroidectomy (half), in 2014. I take levothyroxine, and D3 and caltrate for my bones. I am walking on my treadmill at least 3 times a week, incline 5.5, @ 3.3 mph, but my metabolism is down. I do these exercising because I have to. It takes me 1 hour 39 minutes to go 51/4 miles. I m taking a Liquid B-12, to help my metabolism, but I can do one task,and I m completely tired. The side effects of the thyroidectomy are many....any suggestions?