A small personal example is my watch. I no longer wear one. I don't need a watch to tell time. My phone is always with me and it tells perfectly good time.
My watch battery gave out and I found myself wearing it anyway. My initial rationalization was that if I didn't wear it, I wouldn't have it with me when I got around to going to a jeweler to have the battery replaced. But I laughed at the absurdity of putting on a watch every morning that I knew perfectly well didn't work. Upon reflection, I realized the truth: I was wearing a watch because besides keeping time it is a piece of jewelry and I was accustomed to wearing one.
But for me, there is a downside to wearing a watch. I found that when I was talking to someone, even if engaged and listening intently to what they were saying, I would sometimes unconsciously look at my watch during the conversation. The other person invariably would say "I'm sorry. Am I keeping you?" I was always mortified. I wasn't even noticing the time, it was an unconscious crutch.
So I weaned myself from the habit of wearing a watch. After several months, it no longer feels like something is missing when I don't wear it. In fact, it would now feel odd if I did wear it. I am not suggesting that other people shouldn't wear watches if they like them. I am just saying that it's interesting to see the things we do that no longer make sense, yet we still do them.