You just try to be better day after day. Living whole heartedly in sin and never trying to do better after we give it to him is “making a mockery of this gift”, but not actively trying to do better.

AND if you are not familiar with the doctrine of unity with Christ, you should do some searching on that. It is incredibly understated I think. In a nutshell, when we trust in Jesus, we are IN HIM and He is also in us. It means that when God sees us, he sees the blamelessness of Jesus instead of our sin. And when we are in Christ, there is NOTHING that can change that. A good book on this subject is Home with Christ by Kyle Whorley if you’re interested :)

I don’t know if this helps or answers anything really, but I think that it has a lot to do with our intentions. If you “go on sinning that grace may abound” ans Paul says, then that would probably be as you said making a mockery of our gift of direct communion and also of God’s grace. But of course, like you mentioned, at this present time, sin is inevitable. God knows this, he knew us when he sent His Son. so I think if your heart is in the right place, which our Father knows if it is, then there’s no reason to beat yourself up. Of course we should be obedient, out of our love for God and our thankfulness of His great kindness.