"All have sinned and fall short of the glory of God" is not supposed to be a verse that Christians use to feel guilty about their weaknesses. The very next verse says, "People are declared righteous through the redemption which is in Christ Jesus." Glory means "great value." Redeem means "to restore value." No matter how much we had fallen short of God's glory through salvation in Jesus He much more raises us up to His glory! So you as a Christian never again need to speak of how you "fall short of God's glory." If you still do then you think your value is based upon your behavior. Not even the best behavior could reach God's glorious value but He has given us the value of Jesus as a gift.
To call yourself unworthy is untrue. To say that you "fall short of the glory of God" because of your actions is untrue. What kind of father wants his son or daughter to think that he or she is "unworthy" to be his child. God made you eternally worthy because He birthed you Himself by His Spirit. The bible says righteousness is a gift. God made all His children righteous yet for years I never heard a single Christian say, "I am righteous." At the same time, it was almost impossible to encounter a Christian who didn't speak of their unworthiness.
So many self-professed Christians were taught to look back at their salvation as if it were this:
"I first met my father on Christmas day. He kept telling me how sinful & unworthy I am. I apologized to him. He accepted my apology by saying, 'Now that you've met me I'll tell you how to earn your Christmas gifts from me.' He told me a little but mostly he just kept telling me how sinful I am & how unworthy I am to be his child. He said it was his job to remind me of how much I fall short. Because of my unworthiness I have never been able to receive a single one of his gifts."