Allah says in the Holy Quran, “I did not create jinn and humans except to worship Me” (Quran [51:56]).
Our purpose in this life is to worship the one true God, to submit our will to His, and to seek his love and reward in both this life and the afterlife. Muslims do not believe that the existence of humans or of the universe happened by accident, but rather that we were intentionally put here by the Creator of the Heavens and the Earth, and that our lives are meaningful and successful in so far as we fulfill the purpose He gave us.
Worship in Islam is very comprehensive, however. It includes the very important ritual acts of prayer and fasting, but it also encompasses anything that God has commanded humans to do. Seeking knowledge, supporting your family and community, and even smiling in the face of your brother/sister all count as good deeds of worship, provided that you have the right intention in your heart.
Seen this way, Islam is not meant to be just a ritual act that you perform privately at home, but a holistic way of life. Every belief and value you hold or action you take can be informed by the Quran and teachings of the Prophet Muhammad (PBUH).
In one of the last verses of the Quran to be revealed, Allah (SWT) says, “Today I have completed your religion for you, perfected My favor upon you, and have chosen Islam as your religion” [5:3]. Thus, Muslims follow Islam, because they believe it is the true and complete religion from God, given to us as a favor and guidance to follow.