For me personally: Lonely.
I have severe troubles talking to people, therefore I do not make friends. I haven't done so since elementary school, and I've retained one friend since elementary school. The only exception is a girlfriend I made who I recently broke up with after 4 years. The distorder has no effect online for me, so I met her on a dating site called meetme, got to know her a bit, met her in person a few times. Something happened because it didnt' take long before she became the first person I've ever been able to talk to 100% unrestricted. I spent 4 years just forgetting I even had anxiety because suddenly I have someone I can talk to every day. Now we've broken up and I'm forced to remember I have a serious problem I've been neglecting.
Back in middle/high school I'd often attempt to talk as I walked from my house all the way to my seat on the bus. I never made it onto the bus while talking, nor have I made it within earshot of anyone else standing at the bus stop. It's just a drastic and sudden change in your ability to speak. That's just from being around people. In 12th grade I had to read news reports to the class weekly. I'd always make sure I had two stories written as short as possible, one as my planned story to present, and another as a backup incase someone did my story. Sometimes people would read both short articles I had. I'd rush to find the next shortest article I had and see what I could cut out. Recite it in my head, calm and ready to present it, not a single worry, you got this. My turn, I stand up. My skin suddenly feels like it's on fire and has painful tingling in some spots (i'm unaware thankfully, but i'm deep red). I'm starting to sweat because I actually am heating up from blushing, it's super uncomfortable. I read 1.5 sentences, then it becomes difficult to breathe, and so I am having trouble saying 1/3 of a sentence all at once. I skip half of the article, I've been presenting it too long. The teacher asks a question because he knows details are missing. I have trouble thinking and can't give too great of responses to his questions. I sit down, still sweaty, cooling off, suddenly can think of 100 responses to what the teacher asked, feel relieved. I called that human tomato mode (they don't think or talk, and they're red), but I guess that's a panic attack. Social situations have varying intensities of these symptoms. People will give a small talk kind of greeting and I'll mentally panic wondering what to say so I'm not rude, but also not seem odd or boring. Good luck getting me to have a conversation. I spent 2 weeks isolated with about 15 guys all trying to get me to talk the whole time, all while i'm trying to get myself to talk too. Didn't happen, which is when I first decided I need help getting this fixed. Talking to family is even getting increasingly hard, which is sad because in middle/high school, they were all I had. I've moved back in though so hopefully that reverses. Also working on making new friends, unfortunately that requires I meet them all online first somehow. From what I read, social anxiety differs from person to person in terms of symptoms, severity, and 'triggers'. So that's just me.