These are solemn words of Jesus. He goes Soul Manifestation Review on to talk of branches who used to be in the vine, but who did not remain, and we do not always know the reason. In one sense they may still be around, but of no use to anyone. They are out of office, and out of their calling, and worthless, and isolated from the others, on their own, and apart from those who are continuing to grow. They are severed from Christ and ready for burning. This is serious indeed.
So often Jesus refers to remaining, and continuing connected, and receiving the sap of love and strength and power, and when we are in this situation look what happens.
There is fruit. Prayers are answered. We bring glory to God. Love flows, and His joy will be in you. How do we continue in His joy and love? It seems almost impossible. It condenses down to this one word again - obedience.