A few days back, I heard someone stating that fasting in initial days of Ramadan this year was very tough although with time it is becoming manageable. They also said that by the end of the day, one gets quite grumpy and it becomes even harder then to bear with the fast.
Even before the advent of Islam, Arabs used to make their horses go without food for days in order to prepare them for battles. Similarly, fasting is supposed to prepare one in multiple ways. Refraining from food obviously makes one cherish and acknowledge the great blessings of God. It also makes it easier for one to connect with the feeling that many unfortunate souls experience when they are unable to get food for themselves and their families, and sleep with empty stomachs.
At the same time, Islam also lays an additional emphasis on dealing with others in a nicely way and refraining from hurting them even verbally, especially during the month of Ramadan. In this regard, although one may become easily irritable, the emphasis on self-restraint when one is cranky strongly encourages them to control their temperament. Thus, the fast makes one practice control under severe pressure and difficult situations. When one goes manages composure under such conditions for a month, it is bound to leave lasting differences.
Ramadan, thus, prepares one for the rest of the year both physically as well as spiritually.