In the old testament, the decree was, if you obey my commandments, you will be blessed (Deuteronomy 28:1-2)
In the new testament, the decree is, I have blessed you so obey my commandments (Ephesians 1:3-4)

Think about this: Just as blessings come as result of obedience; Obedience must come as a result of being blessed.
How can we obey God? If we love Jesus, we will obey God’s commands (John 14:15) and it is easy to love God who blesses us with ALL spiritual blessings in Jesus Christ.

Deuteronomy 28:1-2 (KJV)
1 And it shall come to pass, if thou shalt hearken diligently unto the voice of the LORD thy God, to observe and to do all his commandments which I command thee this day, that the LORD thy God will set thee on high above all nations of the earth:
2 And all these blessings shall come on thee, and overtake thee, if thou shalt hearken unto the voice of the LORD thy God.

Ephesians 1:3-4 (KJV)
3 Blessed be the God and Father of our Lord Jesus Christ, who hath blessed us with all spiritual blessings in heavenly places in Christ:
4 According as he hath chosen us in him before the foundation of the world, that we should be holy and without blame before him in love: