It's easy to assume that missionaries are only those who go to foreign lands preaching the Gospel of Christ to people who've never heard it. Christ's command to "Go, therefore, and make disciples of all the nations" (Matt. 28:19) at first even seems to support this romanticized picture. The words "go" and "all the nations" immediately put us in a "somewhere other than here" attitude. It seems easier to get excited about witnessing for Christ when we imagine going to a place where nobody knows us.
While some people end up going to other countries, most of us stay at home, in our own, much smaller world. And that's OK. When Christ first sent the apostles to all the nations, Christianity was unique to a country only slightly bigger than the state of New Jersey. Today, Christianity can be found in nearly every corner of the globe, part of that due to foreign missions, of course; but much of it due to everyday Christians trying to live their everyday lives like Jesus.
Evangelism is less romantic than we'd like it to be. It requires not just talking about Jesus, but living like Him and treating other people the way He did. And it's not just aimed at strangers; it's a lot harder to tell your best friend or your grandma the truth of Christianity, but that's who most of us usually have to tell. Evangelism isn't a point system in which the person with the most converts wins (Christ has all the converts anyway), it's a holistic approach to faith that aims for the transformation of culture itself. This means the spread of the Gospel and Gospel principles through every avenue at our disposal, whether outright preaching of the Word, political involvement, science and art, or any other means available. It is the spread of the kingdom in the hearts and minds of people, as well as in the very fabric of human society.
Christ compared the kingdom of heaven to a mustard seed, saying that it began small but would eventually grow until birds came and landed in its branches (Matt. 13:31-32). Although the task of disciple-making is arduous and often seems entirely unproductive, Christ said, "All authority has been given to me in heaven and on earth" (Matt. 28:18). These are hopeful words, not in the sense of "I hope that happens," but in the sense of something definite we have to look forward to and remind ourselves of. Christ will not rest until all He has appointed are drawn into His fold. As His Church, to whom He gave the command to make disciples of all nations, we shouldn't either.
"For as the rain and snow come down from heaven and do not return there but water the earth, making it bring forth and sprout, giving seed to the sower and bread to the eater, so shall my word be that goes out from my mouth; it shall not return to me empty, but it shall accomplish that which I purpose, and shall succeed in the thing for which I sent it."