God's grace doesn't "make up the difference." It's not that we've got a certain amount of ability to do good, and grace is meant to make up for whatever we're lacking or wherever we fall short. You will not find a definition or description of grace that is anywhere close to that in the scriptures!
The Apostle Paul didn't say, "I put forth my best effort and grace covered the rest." No, Paul chucked aside all his best (see Phil 3:4-11), counting it all as loss, and counting it all as bull dung, so that he could know Christ alone. When it came to living out our daily life and living out our various ministries, Paul said it was all grace. He said that his holiness and sincerity were from God, "not according to worldly wisdom but according to God's grace." (2 Cor 1:12).
Paul talked about his great accomplishments and abundant work that he'd done, but he said, "yet not I, but the grace of God that was with me." "By the grace of God I am what I am." (1 Cor 15:10) Our gifts and callings aren't our own, but solely the result of God's grace. (Rom 12:6). Our ministry/serving is "according to the gift of God's grace" and "the working of His power." (Eph 3:7).
If your ministry is about you and your wonderful work "for God," give it up! Don't be so foolish. "Neither is He served by human hands, as if He needed anything, since He Himself gives to all life and breath and all things." (Acts 17:25). It is God who works in you (Phil 2:13). God began a good work in you and God will be faithful to complete it! (Phil 1:6).