Jocko and Echo both sing the praises of Onnit's Shroom Tech products which claim to help both immune system and physical fitness. Sadly, Onnit products are quite pricy, more than I can justify right now. So I got a generic version.
Been taking these strange brown capsules twice daily for about a week now. This is totally subjective and may be completely placebo but I do feel better and happier. My athletic performance feels stronger and unusually I'm not feeling famished mid-afternoon. No capacity to do a proper double-blind trial but this impromptu experiment does seem to be a success.