Mental Fog

I struggle with “mental fog” a lot. I wake up just feeling blurry or after many interactions with people throughout the day I feel drained. I do take action despite of it but am slower at my tasks despite thinking thoughts like I have done this before I can do it again. I have the energy I need to get this done. The result is not getting as many things accomplished and at times feel like I hit a brick wall. Am I drained because I am resisting feelings? IS there other thoughts I can think?