The mind and body go through natural cycles every day where different parts of our brain and body are more active than others. So we're not always supposed to be involved in activities that require intense thought or concentration every minute of the day. In reality productivity and focus come in waves and it takes training to maintain a specific type of focus for longer and longer periods of time. Obvious examples of this are athletic training and playing a musical instrument. The more you practice, the better you perform.
