I am the vine, ye are the branches: He that abideth in me, and I in him, the same bringeth forth much fruit; for without me ye can do nothing.
John 15:5 (KJV)
Strength and power comes from our personal relationship with Jesus. Walking with Him and being in fellowship with Him through the Holy Spirit gives us might and ability beyond what we could accomplish on our own. The more connected we are to the vine, the more fruit will we bear.