Why Do We Have to Obey God's Commandments?

 To be happy we have to obey the commandments of the Lord. That is what he promised in the past, and it is what he promises today. The Lord is always telling us that we have to be obedient because He has blessings prepared for us. Sometimes we forget that the way to receive those promises is easy, and we start living lives away from God because we think he doesn't care about us. But he cares! That is why he always says in his scriptures that we have to follow him, and obey his commandments. Every general conference we hear that we have to be obedient, because it is a way to help us remember the key to eternal happiness. In Mosiah 2:41 we read “And moreover, I would desire that ye should consider on the blessed and happy state of those that keep the commandments of God.”
Sometimes when we disobey the Lord and we choose to live a life apart of him, we start living the consequences he has stated in his scriptures. In those times of affliction and unhappiness the Lord is sad because he does not want us to live that way. He has given us repentance and prayers to be able to communicate with him again and to live a righteous life. Knowing that God really cares about how we live and if we are happy makes me feel that I have something important to do during my life here on Earth. And it is to obey him and to do what he has asked me to do. 

References:

Deuteronomy 10:12-13; 11:1, 8-9; 13:4; and 26:17-19.
Mosiah 2:41
Doctrine and Covenants 130:20-21
Deuteronomy 4:29-31; 26:7-11
Isaiah 55:6-7
Ezekiel 18:21-23
Mosiah 26:30