Fasting is the quickest way to inter into a self reflective state. When we are on our phones, eating, snacking, smoking and drinking we are using our dopamine. Dopamine is given to us as a reward. Nature gifts us dopamine for accomplishing something. These things that we do to release dopamine require no effort on our end. By the time we finish with our habits, we have no more motivation or reward chemicals and we feel low or depressed.
Ancient traditions and initiate schools also known as spiritual self-improvement schools prescribed fasting. Fast is to abstain from food from sun rise until sunset, some may up even overnight. This allows the body to reset from the external senses. It is a temporary boost.
Because the flesh or the body is nullified by abstaining from the pleasure of eating you will be put into a self-reflective state. In this state, it will be easier for you to connect with your subconscious mind and make changes to your habits and behaviors. Fasting, prayer, and mediation take you out of the routine loop. The mind is not used to having a break in the sequence.
Inner Mysteries 