Romans 8:12 says that we are under an obligation, not to the flesh or its desires and lusts, but to the Spirit. The word obligation seems so negative!  We are obligated to go to work every day, we are obligated to pay our bills, we are obligated to love our wives and respect our husbands, and we are obligated to put aside our own desires and live according to the Spirit. It seems like it is saying that we are being forced to live according to the Spirit but in fact it is our desire. Jesus has laid down His life for us and out of appreciation and love for Him we also lay down our life for Him. 1John 4:15-21 “Whoever confesses that Jesus is the Son of God, God abides in him, and he in God.  We have come to know and have believed the love which God has for us. God is love, and the one who abides in love abides in God, and God abides in him. By this, love is perfected with us, so that we may have confidence in the day of judgment; because as He is, so also are we in this world. There is no fear in love; but perfect love casts out fear, because fear involves punishment, and the one who fears is not perfected in love.  We love, because He first loved us. If someone says, “I love God,” and hates his brother, he is a liar; for the one who does not love his brother whom he has seen, cannot love God whom he has not seen. And this commandment we have from Him, that the one who loves God should love his brother also.

We love God simply because He loved us and we show our appreciation to Him.