When you are driving your car in a 25 mph zone, are you using 100 percent of your car? Yes, but not to it's design limit. In this world, we appear to have a design limit that would exceed our available application. Perhaps this will allow for us to live a much longer life, someday.
the brain is like the muscles. body builder can do a heck of a lot more with their muscles than sitting at a desk me. but, i work my brain and develope and work it. so, it's a matter of, did you start drinking as a teenager and hurt your brain during it's critical stage of development? do work on using it? learning new things? memory exercises? that sort of thing.
we do but we are just unaware of it It happens most when we are sleeping (subconscious) or doing activities (ordering your body to move) requires you using your brain but you just never take it in consideration