Do not be afraid to go out on the streets and into public places, like the first Apostles who preached Christ and the Good News of salvation in the squares of cities, towns and villages. This is no time to be ashamed of the Gospel (Cfr. Rom 1,16 ). It is the time to preach it from the rooftops (Cfr. Matth 10,27 ). Do not be afraid to break out of comfortable and routine modes of living, in order to take up the challenge of making Christ known in the modern "metropolis."
St. John Paul II, 8th World Youth Day - Mass at the Cherry Creek State Park of Denver
Do you have to quote the Bible to preach the Gospel? Remember that your actions speak louder than words. Preach the Gospel in your everday life. Preach the Gospel through the way you speak, the way you treat others, the way you dress, the music you listen to, the way you respect the lives and bodies of others, etc.
Show your classmates, friends, co-workers, and people that you run into in shops and stores, that you follow Christ, and you aren’t afraid of showing it. How many people are waiting for your example? How many are waiting to see people who live their faith in all aspects of their lives, not just in their words? How many people would start fighting to live a good life because of the example you set for them?
Do not be afraid. It might be a challenge, but it will be worth it.