"But he wasn't even trying!" Cain must've thought.
No, he probably wasn't. Abel was too busy looking at God and grateful for what God did, to think about himself. Abel's mind was filled with how God rescued us from our miserable state with the shed blood of His only Son--and how we could commemorate that with a sacrifice lamb. Hm; Abel probably didn't think about making the yucky offering more attractive or of trying to make himself better.
Me? Sigh; I guess too often I'm like Cain and want God to look at what a prayerful person I am; what a loving person I am; what a hard-working person I am; what an honest person I...you get the idea. I try to make myself into a person God will feel lucky to have believing in Him--as Elizabeth Elliot once said: I am so ridiculous!
Father; help me, like Abel, to get so taken up thinking about all You've done for me I forget about myself.