The fourth pillar of Islam is fasting the month of Ramadan. Here is a brief introduction to fasting. This is a beautiful pillar of Islam. It is a means of control. We give up something that will benefit us spiritually and physically.
Fasting the month of Ramadan is a conditioning and discipline of the soul and of the spirit. We define discipline here as consistent acts of will power. When you see that sweet or bread that you crave but leave it, that is will power. Consistently doing it is discipline.
Every thing that Allah instructs us to do is so that we will be disciplined to fill our ultimate purpose in life. Ramadan does that. It makes us mindful.