Everyone confesses in the abstract that exertion which brings out all the powers of body and mind is the best thing for us all; but practically most people do all they can to get rid of it, and as a general rule nobody does much more than circumstances drive them to do.
Bio: Ivan Petrovich Pavlov was a Russian physiologist known primarily for his work in classical conditioning. From his childhood days Pavlov demonstrated intellectual brilliance along with an unusual energy which he named "the instinct for research".