Even people like Helen Keller were taught a symbol system that allowed them to communicate and express abstract thought. But this is not what I had in mind when I gave my examples. I was trying to communicate that feeling we have all experienced when we are performing some complex activity, such as art or sports, that does not require abstract reasoning and symbol manipulation.

Consider a race car driver negotiating the turns, coordinating gearbox, wheel, throttle and brakes to maximize the performance of his machine.
There is an enormous amount of mental activity going on, and it obviously takes a great deal of practice to master these skills, but there is no conscious symbol manipulation taking place. Language and self awareness and symbolization may play an enormous role for the driver when he is preparing himself and his car for a race, but on the track, it simply flows out of his brain effortlessly, unconsciously, unawares.

And when the race is over, he is exhausted because it is hard mental work.