Same happened to me, but I was at a point in my life where I didn't need to do a lot of deep thinking so I continued anyway, and after a few months my body had

Same happened to me, but I was at a point in my life where I didn't need to do a lot of deep thinking so I continued anyway, and after a few months my body had grown accustomed to it. I can now push myself to my limit and will feel fine after 15 minutes.