I think it really depends on the person. I always get an energy boost heading to the gym and I find my mind is clearer from the endorphin rush. Some people are clearer out of bed; I have had allergies to pollen and the environment all my life, so going to the gym clears it for me and I find I am more productive as a result. I go to the gym twice a day, akin to getting a cup of coffee to helping me focus.

Exercise and fitness is different for everyone. I don't think there is a single categorical way to approach exercise other than that you do it.