Holiness simply means to be set apart or to be different. Different from what? Different from the world. Both holiness and worldliness are about focus. Worldliness is about focusing on imperfect human effort. Holiness is different in that it is about focusing on perfection which is embodied only in Jesus. Jesus is enough for all of life.
Holiness is about the experience of being aware that Jesus is enough--that both 1) his perfection is the only good measuring stick and 2) his death is the only good resolution for the problem of human failure. This easily and naturally applies to all human relationships in all circumstances. Life flows freely from a heart while it is satisfied with goodness. A satisfied heart doesn't struggle, but rather responds to others as valuable people. This is what it means to be human.
Worldliness is the distortion of what it means to be human. It is a focus that doesn't see the whole picture of life, that only perfection is good. Life becomes a check list of good and bad thoughts and actions. I doubt that you appreciate people seeing you as part of their check list. No one does, but there is no other way to function when perfection is not in view. Goodness is shattered and the only way forward is to try to pick up the pieces one by one. Trying mocks doing, mocks our humanity, and mocks goodness. It bears the ugly fruit of the works of the flesh (Gal 5:19-21). Worldliness denies goodness as a real experience.
Humans live only in the current moment. Therefore, in the current moment we either see life as a check list of ideals (kindness, patience, self-control, love) to strive for, or as perfect goodness to experience now. As you notice human behavior, do you occasionally get distracted into forgetting the big picture that goodness includes perfection, or do you always maintain awareness that only perfection is good? Where is your focus? You can't do perfection, nor can anybody around you. But Jesus did, and his life flows out of you when you simply focus on His goodness (His perfection and His sacrifice for sin). Trying is like a hamster wheel. Only the hamster thinks he is getting somewhere.
Note: In a recent sermon (listen here) in Hebrews 10, I explained how the world is all about trying and how trying is a lie. The sermon visual aid (white board photo) can be seen here by scrolling down to Hebrews#35.