Beauty is Skin Deep
Beauty fades with age, and our appearance no longer has the same effect on people. It is good to present yourself in the best way that you are able. The Bible says that beauty is passing (Proverbs 31:30). However the inward appearance, the inner man is what really matters (Ephesians 3:16).
When we say beauty is skin deep, we are trying to encourage people to develop good and wholesome character. That grows through a relationship with our Creator and respect toward Him and His way. That is the definition of lasting beauty. That is the kind everyone can develop as they take care of the outward appearance. The inner man grows in beauty even as the outer appearance fades.