1.Just becauae someone isnt intrestes in you doesnt automatically mean they are rejecting you as person.They maybe busy, distracted or have other things going on.
2.If someone does reject you that doesnt mean that you are worthless or unlavable.Maybe they are having a bad day. Maybe they misread you or misinterpreted what you said or Maybe they are just not a nice person.
3.You are not going to like everyone you meet and vice versa.Like dating, building a solid network of friends can be a numbers game. If you are in the habit of exchanging a few words with strangers you meet, rejection are less likely to hurt. There is always the next person focus on to the longterm goal of making quality connections rathet than getting hang up on the ones that did not pan out.
4.Keep rejection in perspective: It never feels good but rarely as bad as you imagine. Its unlikely that others are talking about it. Instead of bitting yourself up, give yourself for trying and see what you can learn from experirnce.