Many people ask this question, but if a person is a true believer, you are a disciple of Jesus Christ and you have surrendered to Him as Lord and you are completely in His hands. If He is truly leading you, it's never too late to start; it's never too late to begin. It may be likely that you need wise, godly counsel to either find the right niche or to find the right allocation. But God can surely use you.

You want to follow Jesus for the rest of your life, whether you are in ministry overseas, or in ministry in your own country/culture, or you are just "an average Christian" in a local church who shares in the missionary vision and prays for missions, but has a full-time job and family and cannot spend as much time in missions issues as you might like. Sometimes God changes our circumstances and God’s providence changes our status from being overseas to coming back home to the USA or your home country/culture. If you are surrendered to Christ as Lord, don’t worry about the question, “how long do I have to commit to missions?” Just follow the Lord and abide in Christ, the true vine, every day. (John 15:1-16)