Five times a day prayer rituals are practiced. The repetition of prayer throughout the day is supposed to strengthen the relationship with Allah. The third pillar is Zakat. Zakat is the act of donating a percentage of annual wealth to other Muslims that are to as wealthy. This helps to create equality among members. The fourth pillar is fasting. Fasting is recommended frequently for Muslims but is only required during Ramadan. Fasting is a way to cleanse the mind, body and soul of impurities.
It also provides the opportunity for those who have more to understand what it is like to not have. The fifth pillar is Hajj. Hajj is the act of traveling to Mecca. Those who are physically able to travel and can afford to do so are expected to travel to Mecca once in their lives. This is expected to bring people of the faith closer to Allah. There are various sites in Mecca where various rituals are performed. These Five pillars are the basis for the Islam and Muslim religion.
Each of the Five Pillars represents very important aspects of this faith. In my eyes, daily prayer would probably be the easiest of the five even though it would be time consuming. Of the five, I think that fasting would be the most difficult. Forcing yourself to not eat would be very difficult. Although this is only done during daylight, during the summer the days can be long. This would make the day very uncomfortable, but Im sure the body adjusts to it.