Think of something you believe God wants you to do. You have thought about this for some time, but you have never been able to do it. What is the problem? Possibly you have not been faithful in small matters (see Lk 19:17) so that God has not promoted you to greater things.
For example, for decades we have been trying to stop abortion, reverse the seemingly relentless march of the culture of death, and replace it with a civilization of love and life. We are sure the Lord wants us to do this, but we have not been successful in doing it. Possibly we have not been faithful in smaller matters, such as praying with our spouses, shutting off the TV, going to Confession regularly, fasting frequently, speaking of Jesus at work, etc.
The Lord has "an eye for detail" — detailed obedience. If we are obedient across the board, we can do great things by bringing down the strongholds, lies, and pretensions of the evil one (2 Cor 10:4, 6). We can even make every thought captive to Jesus (2 Cor 10:5). We can do greater things than Jesus did (Jn 14:12).
Jesus was faithful in small matters, such as many years of obscurity, family life, and manual labor. He was entrusted with the greatest work — the salvation of all people. Be faithful as Jesus was faithful.