In their book Total Church, Tim Chester and Steve Timmis hit the nail on the head:
"The term mission is from a Latin word meaning "sent." Jesus sends is followers out into the world with his gospel word to make other followers who will go out into the world with his gospel word to make other followers in perpetuity. Missions begins in our own hearts as the gospel word of Christ crucified is effectively applied by the Spirit. And it does not stop until the far corners of the world. It is a constant continuum because mission is what we might call the steady state of God's people." (Total Church, p. 101, emphasis mine)
The bolded statement resonated with me when I first read it, almost getting my attention like fingernails on a chalk board. Do we really believe that our hearts need to be evangelized? Do we know our hearts need the gospel? Our need of the gospel is not a once and done sort of thing as we are to grow in the grace and knowledge of the Lord Jesus Christ. This is essentially growth in the gospel.
This statement reminds me very much about Richard Baxter's words in The Reformed Pastor that a preacher must first preach to his own heart. Well a missionary must first evangelize their own heart. We must make sure that we are delving into the riches of God's mercy given to us in the gospel. We must know through personal experience and confidence that having seen the condition of our heart and seeing where it is now that the gospel really is the power of God. Paul really didn't have any great missionary secret other than a deep seated personal conviction that the gospel really is the power of God. That knowledge and conviction brings boldness beyond what we could ever ask or imagine.
There is of course a danger is being too individualist and introverted when we say "missions begins in our hearts." The simple solution there is to grasp the reality of Christ crucified: it is for God's glory. It is to bring worshippers to God. As John Piper has said: "Missions exists because worship does not."
I think there is a better way to apply Acts 1:8 than drawing circles around our church and moving outward. But by the same token, I'm not advocating we 'draw circles' outward in terms of our spheres of influence, although it might helpt to identify people in your life with whom you have contact, the level of contact and relationship you have with them and how to best share the gospel. What I am suggesting, is that I need to recognize the evangelism that the Spirit did in my heart. He used and uses the preaching of the gospel to save me and conform me to the image of Jesus, from one degree of glory to another. While my feet must be fitted with a readiness of gospel my job is proclamation--it is the job of the Spirit who Christ sends to actually apply 'Christ crucified' to the hearts of sinners. It's not about you and how suave you are, it's about Him and His power. And that too is good news.