When this happens, there seems only one plausibility: run. You think that if you could just up and leave, start a new life, maybe you could outrun illness. You picture this new life in which you're in some new town or foreign city, where you've somehow managed to make work everything that you can't now. In this new life, you're not socially anxious - you can actually talk to people and make friends. In this new life, you can actually handle stressful situations without melting down and crying. In this new life, you have skills and talents that actually make you feel like you have something to offer. And you have confidence that make you feel "worth it", able, capable. And you actually are. You feel that if you could just start fresh, you'd be OK. You'd be able to get up in the morning without dread. You wouldn't feel so dark and lonely and alone. You wouldn't be so anxious, so fearful.
Now let me clarify, this generally has nothing to do with specifics. It's not that you're unhappy with your friends or family or partner. It's not that you dislike your job. It's not that you're ungrateful and think you have it so bad, or lack perspective. It's just that you physically, mentally, emotionally need to get the hell out of dodge, and you feel like you'll break if you don't.
I'm not going to sit here and give you platitudes. You'll get no "but there are starving children in Africa" guilt from me. Because that's not the issue. You know it's not, and I know it's not. The issue is that you feel like you just don't belong in your life. Those closest to me will often hear me say, in my darkest moments, how I feel that I don't belong in this world. Like I was born in the wrong century in the wrong place, and that no matter how far I wander, I'll never feel at home. Because even if I get to the right place, wherever that is, I'll still be in the wrong century. It feels like I'm hollow, unfulfilled. Like until I find the "right" place and time I can't understand why I'm here. It feels lonely and isolating, and worst of all, I blame myself for it. It feels that if I can just run far enough, maybe I can outrun that self-blame. But that no amount of "you do so much good" or other similar words will help. The only words that could possibly help would be "wherever you run to, I'm going with you" (by someone close - otherwise that's called a stalker). Because at least I know I wouldn't be alone.
I wish I had a solution to offer. I don't. But I can tell you that I know what it's like. And if it helps you to vent to me, to tell me all about where you'd run to and what you'd do and what you dream of your life being, then I'm happy to listen. Imagination can offer hope, and sometimes, it's enough hope to lessen the need to run away. Or perhaps knowing that someone else understands helps you to feel less alone. Less estranged from everyday life, from the world as a whole. The only other thing that I can suggest is to create a system of "mini breaks". Perhaps it's that you have a notebook, or a bulletin board, or a jar in which you toss written suggestions of those ways to give yourself a mini break without actually having to run away. Maybe it's going for an actual run. Maybe it's taking a drive, or a day trip out of the immediate area. Maybe it's doing something fun that you don't often do - something that reminds you of your childhood, or a happier time. Perhaps it's simply writing out your feelings, or daydreaming with a friend. Try to think of those things that could take the edge off the need to run away. They may not solve it all together, but they may give temporary reprieve. Hopefully, the need will eventually pass. I realize that doesn't offer a ton of hope, but it is, unfortunately, the best I have. And always, know that you aren't alone.