Reflecting on my life, I think there is a mind body connection. And your brain doesn't work properly unless you also exercise. The best shape (post university) and sharpest I felt is when I played tennis daily. It just seems to be a sport that improves everything; reflexes, strength, cardio, speed. And I just felt very sharp physically and mentally during period. Hiking, and especially kayaking are like the antidote to brain rot for me now. Sitting in a kayak, watching a sunset on lake, surrounded by birds and wildlife and nature, it just kind clears your mind. Kayaking seems to have just the right amount of effort (you can go at your pace) and relaxation (provided you're in calm water) and nature and novelty, that it seems to connect you back to the world. Interestingly, many of the former US presidents where also big fitness buffs.