In order to make lactate, you have to work hard; you have to be going 85% of your max heart rate, and doing that 10, 20, 30 minutes, right? The more you do it, it's a dose-dependent effect. That lactate goes into the brain.... and it increases something in the brain called brain-derived neurotrophic factor, BDNF ... It's something that increases the growth of new neurons in the hippocampus. It increases the connections between neurons .. And it also improves something called neuroplasticity. So that is the ability of your brain to adapt to a changing environment.