Since we are the branch through which the life of God flows, we sometimes think that it is our own holiness that produces the fruit. The moment we think that way, we are no longer abiding in the vine and we will become fruitless if we persist in thinking this way.
This is actually a relief if the believer understands this and applies it properly. It puts all the responsibility on Jesus. Our only responsibility is to respond to His ability. In the same way that you have never seen a branch travailing to bring forth fruit, so all we have to do is labor to enter into His rest and completely trust Jesus as our source (Hebrews 4:11). If we abide in Him, fruit will come naturally.
It's our faith in what Jesus did for us that saved us, and our faith has to continue to be in Christ, not in ourselves, to maintain salvation. Our holiness, righteousness, and justification are gifts that we receive in our spirits through Jesus.
Just like the life of a root is found in the soil, or a branch in the vine, or a fish in the sea, so the believer's true life is found in the union with Christ.