@trinsec I think you were right. Went for a walk and feel x4 better. Funnily enough, read this a few minutes ago:
"After years of floundering, I think I'm finally getting it: You get energy by spending it. The fuel tank metaphor is completely misleading. The body supplies energy to meet demand. The tank *expands* if you use a lot of fuel. In other words, biology is fundamentally antifragile. "