Frustrated? It may be because you're trying to make something happen that only God can make happen.
Whenever you are doing what God has called you to do, it is important to rely on His strength, His grace, and His power to complete your task. You will become frustrated if you try to make things happen on your own strength instead of relying on God. God is the author and finisher of His plans (Hebrews 12:2), and you must not try to take the place of God if you expect things to work out.
In Colossians 1:26-27, Paul reveals a mystery that has been kept hidden for ages and generations... Christ in you, the hope of glory. In other words, there is something that people of the past didn't know—it was hidden from them, a mystery to them—but Paul is now revealing that mystery to us: Christ lives in all who believe in Him! No longer is God just with his people—God now lives in his people!
Also, note that it is Christ in you that's the hope of glory—not Christ and you.
Paul then continues by saying that he labors and works for the gospel, but all of his labor is really done by Christ's power, which so powerfully works in [him] (Colossians 1:29).
If you're trying to labor without Christ's power at work within you, then your labor will be frustrating and in vain. You need to stop trying, and start dying to self so that you may be alive to Christ's power.
Struggle and frustration occur when you try to do God's job by your own strength—rather than relying on Christ's strength, which is at work in you.