Mental math is way harder. Neuroplasticity or lack thereof also way more noticeable. Previously I feel like I could learn a new subject/topic pretty quickly, n

Mental math is way harder. Neuroplasticity or lack thereof also way more noticeable. Previously I feel like I could learn a new subject/topic pretty quickly, now it's taking way more time. That said at the same time having noticed this "problem" I now always do a double take on whether I need to really learn something new(cos opp. cost is way higher), so at the same time more pre-commitment => less garbage in my brain.