I have worked and struggled so hard to be a "good Christian." I always felt I wasn't good enough, that God was always disappointed in me, that His main message to me was "try harder." Then He showed me the difference between law (or works/effort) and grace (free gifts). One big difference is "do" vs. "done."
It's the difference between "I'm trying to kill off my old self," and realizing it's already dead.
It's the difference between "I am trying to get forgiveness and redeem myself," and realizing I have already been forgiven and redeemed.
It's the difference between "I'm trying to be holy," and realizing I have already been sanctified (made holy) and perfected forever.
It's the difference between "I'm trying to get closer to God," and realizing my humanity has already been joined as one with His divinity.
It's the difference between "I am trying to get to heaven," and realizing Christ already brought me there.
So many of the things I was trying so hard to do under law were actually already done for me! When were they done? Well, about 2000 years ago. It's called the finished work of Christ because it is truly finished. Yes, believing it allows me start experiencing it personally in my present life, but the fact is, it was already done long ago by my wonderful Lord!
It's the difference between "do" and "done!"