How to get over people not being kind back?

Hi there! Recently, I (21) have made more of an effort to get out of my shell and be more amicable towards others. I enjoy doing so because it’s led to more positive interactions. However, there are times when people aren't at all receptive.

Now granted, I do know that people have bad days, and I do try not to get overzealous. Mostly, I've started doing it at work, and I’ll usually just smile and say hello to people. If a conversation ends up coming out of it, all the better. But like my title states, some people just aren't receptive. I've had people at work or in public gatherings just flat-out ignore me or even look perturbed after this. I'd say I'm just an average person overall as well. I dress casually or more formally if the situation calls for it, and maintain good hygiene and outward appearances.

I'm wondering if I'm just reading too much into things. Sometimes it does make me feel a bit bad because I end up with the feeling that I've wronged this person in some way.

Any advice or opinions would be appreciated!