Brain fog, tiredness & eyes blurring when doing important tasks

I've been on my personal development journey and Dr K content has been very crucial in my journey, made quite a lot of progress in the last year. But there's something that has been recurring lots lately which is as the title says:

My eyes go foggy and I suddenly get tired / blocked / can't think when it comes to important tasks. I know it's probably a protective mechanism to prevent disappointment, but I know I want to overcome it.

Has anyone experienced and overcome this? Dr K do you have any tips? Much love to you and HG team!