We could sum up the great commission in this sentence. The risen Messiah has commissioned us to continue his disciple-making ministry in his authority throughout his world with his presence accompanying us the entire way.
16 Now the eleven disciples went to Galilee, to the mountain to which Jesus had directed them. 17 And when they saw him they worshiped him, but some doubted. 18 And Jesus came and said to them, “All authority in heaven and on earth has been given to me. 19 Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, 20 teaching them to observe all that I have commanded you. And behold, I am with you always, to the end of the age.” 
I am with you (ἐγωμεταὑμων [egō meta humōn]). This is the amazing and blessed promise. He is to be with the disciples when he is physically gone, with all the disciples, with all knowledge, with all power, with them all the days (all sorts of days, weakness, sorrows, joy, power), till the consummation of the age (ἑωςτηςσυντελειαςτουαἰωνος [heōs tēs sunteleias tou aiōnos]).
That goal is in the future and unknown to the disciples. This blessed hope is not designed as a sedative to an inactive mind and complacent conscience, but an incentive to the fullest endeavor to press on to the farthest limits of the world that all the nations may know Christ and the power of his Risen Life.
So this text closes Matthew’s Gospel in a blaze of glory. Christ is conqueror in prospect and in fact. Christian history from that eventful experience on the Mountain in Galilee has been the fulfilment of that promise in as far as we allow God’s power to work in us for the winning of the world to Christ, the Risen, all powerful Redeemer, who is with his people all the time. Jesus employs the prophetic present here (εἰμι [eimi], I am). He is with us all the days till he comes in glory.
I don’t know about you, but sometimes when I awaken in the morning, or am sitting in heavy traffic, I don’t always FEEL his presence. But as our text points out, as we make disciples and are moved to action doing so, His presence is promised at every emotional level we may experience.
That keeps me going! Be encouraged today, no matter what you may be experiencing as you are making disciples, He is with you every day in weakness, sorrow, joy and power until the consummation of the age. His coming again will usher in a time when you will have all good feelings, all of the time, and no traffic jams! Let’s make disciples with His accompanying presence.
 The Holy Bible: English Standard Version. (2001). (Mt 28:16–20). Wheaton: Standard Bible Society.
 Robertson, A. T. (1933). Word Pictures in the New Testament (Mt 28:20). Nashville, TN: Broadman Press.