Caffeine combined with L-Theanine does seem provide slight boost for focus to me. That said, I think biggest mood/focus/energy difference (besides a nice workout which is also important) for me was getting vitamins and other micronutrients in order. I highly suggest you to do a blood test or two per year for all the common vitamins/micronutrients to see which you need to fix. For men, I think it is especially importa…
Potassium: https://www.famnom.com/nutrient/1092/