L-theanine is one of my favorite energy boosters.
L-theanine is the active ingredient in tea (especially green tea), i.e. it is the tea-equivalent of caffeine in coffee.
L-theanine works synergistically with caffeine, improving the activation of my mind (clearer, faster thinking), higher energy (physically and mentally), without becoming jittery or too speedy. The feeling for me, is a meditative-like focus, a quiet awareness, and it seems to sustain me for a few hours. This synergizes really well with meditation and binaural beats.
I get L-theanine in a pure white powder form. It tastes only slightly bitter to me; so little, that mixed into (Bulletproof®) coffee I can’t detect that bitterness.
I add about 200mg by measuring spoon to a full coffee mug.
I use it approximately once a day. In the rare situations where I’m quite tired/foggy but have to be sharp, I’ll use it up to three times in one day.