In Genesis 4, Cain and Abel each bring an offering to God, an offering of fruit and of a firstborn lamb respectively. God found Abel's acceptable, but why not Cain's?
When I worship, my heart must be in it. It must include true faith and a character of humility and devotion. The Lord said to Cain, "If you do well, will you not be accepted?" (Genesis 4:7) Fruit or flock was not the issue, but Cain's attitude. There was no contrition, no faith, no love or adoration. It was, at best, an offering of duty, and more likely one of greed and rivalry and pride. Cain gave in hopes of getting.
There is more to verse 7, "And if you do not do well, sin is crouching at the door. Its desire is for you, but you must rule over it." Sin has a life of its own, crouching as a beast waiting to spring and strike and devour. It craves repetition until it takes hold and becomes a habit. My dad always said, "The problem with kittens is they grow up to be cats." My dad did not like cats. How often to we keep little sins as pets? They grow up.
My wonderful God, may my life be the first thing I bring to You as an offering, as worship. I shall love You with all that I am, my heart and soul and mind and might. And sin I shall hate. You are going to have to help me with this. Please, do whatever it takes.