1In the year that King Uzziah died I saw the Lord sitting upon a throne, high and lifted up; and the train of his robe filled the temple. 2Above him stood the seraphim. Each had six wings: with two he covered his face, and with two he covered his feet, and with two he flew. 3And one called to another and said:
"Holy, holy, holy is the LORD of hosts; the whole earth is full of his glory!"
4And the foundations of the thresholds shook at the voice of him who called, and the house was filled with smoke. 5And I said: "Woe is me! For I am lost; for I am a man of unclean lips, and I dwell in the midst of a people of unclean lips; for my eyes have seen the King, the LORD of hosts!"
6Then one of the seraphim flew to me, having in his hand a burning coal that he had taken with tongs from the altar. 7And he touched my mouth and said: "Behold, this has touched your lips; your guilt is taken away, and your sin atoned for."
8And I heard the voice of the Lord saying, "Whom shall I send, and who will go for us?" Then I said, "Here am I! Send me."
Do you see the progression? God's glory revealed into his brokenness ("I am ruined!"), which is the perfect storm for gospel wakefulness (the severe mercy of the hot coal atonement for his sins), which creates both the qualification and the boldness to be sent on God's mission.
As Piper writes, "Mission exists because worship does not."
But missionaries exist because worship does.
"Missional" will always be a program or a buzzword if you have not experienced the power of the gospel in your own life. The deeper it has exploded in your heart, the more confident in its fruitfulness you will be.