Love is the great motivator for obedience. Not duty, nor fear, but love. And not just any kind of love, but God’s kind of “agape” love, which is both unconditional and sacrificial. So love motivates obedience and then obedience becomes the evidence of that love.
What is love? That we obey Christ’s command (John 14:15). And what is Christ’s command? That we love one another just as He loved us (John 13:34-35).