Maybe I can help by giving an example of my own weakness when it came to vanity for me once.
I was diagnosed with an illness that required treatment with high (very high!) doses of prednisone. This causes one to retain fluid, swell, get a VERY round face, and have an incredible appetite.
I developed all of those side effects, and also developed what is called a “dowager’s hump” or a hump at the very base of the neck - also caused by the steroids.
I found myself explaining to people I was meeting for the first time that “this isn’t how I usually look, it’s from my medication,” and I also found myself isolating and not socializing with my friends because I hated how I looked.
Prior to this I used to take great pride in the fact that I was not a vain person.

I never wore make-up, didn’t get into all the fancy clothes that a lot of women my age did, etc.
I was quite surprised at how vain I truly was and also pretty ashamed. Unfortunately for me, all of this was happening to me before I had found my way back to God and my faith, so I felt very alone as I went through all of this.
But all is good now! Not only do I have God and my faith, my illness is in remission, I’m off the terrible drugs and I’m learning more every day about how God loves me (and all of us) for what He put together
inside of us.
Hope this helps.