One of the most amazing gifts God gave mankind is the conscience. The conscience tells us when we have done something wrong that needs to be remedied. While impenitent sinners are said to have "seared" consciences (1 Timothy 4:2), God disciplines believers when they do wrong, causing them to move back to the correct path.
When we sin, it's not entirely uncommon to try to hide it. Maybe even attempt to justify it. But over time, this becomes a heavy burden. As David said, unconfessed sin makes our bones go brittle. Perhaps, at some point in your life, you've felt something like that. You've done something wrong, and you feel so guilty about it that you literally feel like your body is failing.
David also gives us the solution. "Then I acknowledged my sin to You, and I did not conceal my iniquity. I said, "I will confess my transgressions to the Lord," and You took away the guilt of my sin." (Psalm 32:5).
To think we can hide our sin from God is absurd, to say the least. It didn't work for Adam and Eve, it hasn't worked for anyone since. But what works without a hint of failure is to confess to God what He already knows, and bring ourselves back under His authority. Once we have confessed, He is faithful and just to forgive us, and more importantly, cleanse us from all unrighteousness (1 John 1:9). The more you confess that you are not like Jesus, the more like Jesus the Lord will make you.