Stress to Impress

You hear the term "dress to impress" a lot. But what about just trying to always impress either a group of people or just that one person that you want to maybe prove yourself to. (And I'm speaking to myself here too.)

My question is, why do we always feel the need to impress others? Why can't we just do what we want, say what we want, wear what we want, post what we want, without wandering what other people are thinking of us? 

I think we as humans are constantly fighting this battle against Human Comparing Syndrom (HCS). We always find the need to impress, or up ourselves in the sight of others. But why? What in our makeup makes us think we have to prove ourselves? 

I think instead of trying to answer that question, we all just need to work on accepting our own selves. Our quirky personalities, the way we all think differently, and use that to our advantage, instead of tearing ourselves down constantly wondering what others are thinking of us.