Anyone with weakness or exercise intolerance should try acetyl carnitine. This has proven beneficial effects in the elderly anyway and the HIV community has used it for over a decade now.

Body builders use it in high dose, but people like us may see improvements at just 250mg a day or so. (up to 2 grams if necessary in divided doses). I use Puritan's Pride form, as it it pretty affordable from them.

Carnitine enables mitochondria to use fatty acids when glucose is low. It helps transport the fatty acids across the mitochondria membranes for metabolic energy. I found it very helpful back when I was going to the gym alot, but now I don't use a gym, but still the carnitine helps with stamina and climbing stairs for me now. If I skip a day or two now, I really feel the difference!