It's a mark of His love for us that the Savoir commands us to repent. He wants to forgive us. He wants us. And so He commands us to repent. Knowing that the process is difficult, that sometimes it is all we can do, He promises to be with us every step of the way:
The Lord is not slack concerning his promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance.
-2 Peter 3:9
"Big" sins or "small" sins - the effect of any sin is ultimately the same: separation from God. But He loves us, and He doesn't want that to happen for us, and so He extends us Grace. He commands us:
Therefore repent ye, repent ye, lest by knowing these things and not doing them ye shall suffer yourselves to come under condemnation, and ye are brought down unto this second death.
He wants us, even when it's hard to give up our sins. Even when we stumble. Even when we stumble more than once. His Grace is sufficient; keep trying.
Christ asks us to show faith in Him, repent, make and keep covenants, receive the Holy Ghost, and endure to the end. By complying, we are not paying the demands of justice—not even the smallest part. Instead, we are showing appreciation for what Jesus Christ did by using it to live a life like His. Justice requires immediate perfection or a punishment when we fall short. Because Jesus took that punishment, He can offer us the chance for ultimate perfection and help us reach that goal. He can forgive what justice never could...
-Brad Wilcox, His Grace is Sufficient, emphasis added