"What is impossible with man is possible with God." - Jesus in Luke 18:27
"Missional living" is a term coined by Karl Hartenstein in 1934. Karl was a German missiologist who coined the term to describe a disciple of Jesus Christ who is actively living their life looking for opportunities to build into Christ's kingdom through their everyday lives. He argued that every Christian was called to complete the Great Commission - not just pastors and missionaries.
People who are living missionally are seeking Jesus, asking him to show them his mission for each and every day of their lives. They are people who leverage current relationships to engage in spiritual conversations to lead others to Christ, disciple them to become mature believers, and teach them to live their lives in missional ways. They are people who are willing to start new relationships for the purpose of speaking the truth of scripture into others' lives; hoping they too will become followers of Christ, develop into his disciples, and choose to live their lives in a missional way.