I remember in my earlier days of math classes all throughout school up until my latter years of high school, I did very well without even trying. I literally never studied for tests even once, and I only opened the textbook to rush through the homework in 10 minutes so I could play computer games all day and night after school. I still maintained a 100% average in the classes until pre-calc came along. My grades started dropping drastically as I kept up my lifestyle to about 75%, and when I barely passed pre-calc, I eventually came to fail my Calc class in my senior year of high school. I've read in articles that the brain functions optimally when we're at our youngest, and slowly begins to decay as the years go by...so I'm wondering how I could have possibly gotten by all those years without even trying and then all of the sudden become terrible at the subject. Is it just that the material became significantly more difficult, or maybe did something else happen that I'm not consciously aware of?