How do people get themselves into the mindset of doing what they want when they want, and don't let opinions of others control their self-worth and decisions?

I'm not an introverted person or generally socially self-conscious, so I don't really get why I still let it get to me when I know, deep down, it shouldn't. It's hard for me to understand what goes through anyone's mind when they're going out in public and doing just anything they want like that, without any regard to what others will think. <br><br>For example, I was in the store yesterday and I grabbed a bunch of candy and a big bottle of wine and was going to take it up to the register, then to the car, and I just was worried about what others were thinking about my purchases. It's not an addiction thing, or an over-consumption thing, it's just that I had a shit day and wanted to reward myself with the things I love, ya know? We all have those days and I was ready to do whatever I wanted, and people just gave me weird looks when I was purchasing it. It's just food for thought, and I'd like to know what, if anything, goes through people's minds when they enjoy their life and whatever habits they have, and how they let opinions of other people go?