Fearing the worst

I know the problem to some extend, I think the best you can do, is to confront the fear, get in situations that frighten you and learn that it doesnt kill you. You will after a while find out, that many of the things you are afraid of, are not as horrifying as they seem. They just seem that way, because you dont know what will happen, but if you loose your job, you can find a new one. if your relationship breaks apart, you can fix that, or learn from your mistakes for a future, better relationship. Even if you become homeless, you can get your shit together and find ways out of this situation as well.

 

Life is scary. Having responsibility is scary. Knowing, that if you mess up, people you care for could be effected is scary.
I am not suggesting that you put youself into dangerous, lifethreatening situations, you have to confront the things that actually scare you. If you are afraid to mess up at work, thats a good thing, you should be. That means you care, maybe not even about the work itself, but about things that are connected to it. Learn to do the best job you can.
If you are afraid to do something wrong always keep in mind, that everyone fails, learn from mistakes, take on challanges, ask for advice if you have to.

 

I recently went in a convenience store like I've always done. It seems like (or somewhat all of time) I always mess up and tend to agree with cashier or someone's response and I can't help but say the wrong thing. This has always prevented me from going into any store which depressed me even more. It doesn't help me improve my low sel-esteem, and I go it alone and try to recover--just like turning off porn and other simple pleasures. Getting too old for this.

 

That sounds like you have pretty big issues with anxiety if its difficult to go shopping for you. Not sure what to suggest there, but you have to adress this in some way.
I will just throw out a couple of tipps that helped me to some extend:
- remember that most people dont care about you, sounds bad, but if you think about it, it doesnt really matter if you said something stupid to the cashier, they really dont care, they have to deal with a lot worse shit everyday and this goes for a lot of situations. People do and say embarrassing things all the time and really nobody cares most of the time.
- work on your selfesteem in multiple areas, you probably heard most tips already, just pick a few things that might help you, to me sports, long walks, cleaning my room, working helped a lot. But there are more options, meditation, the right music, less caffeine and nicotine, healthyer lifestyle and so on.
- this might not be possible, but if you can, find a superextroverted friend, the type that is always talking and seems to know pretty much everyone and their grandma. Trust me, this type of friend might annoy the shit out of you sometimes, but you will benefit in multiple ways: you will always meet new people and work on your social skills, and you will soon find out that it doesnt really matter if half the shit you are talking doesnt make sense.
- go to a forrest from time to time, its beautiful and is proven to reduce anxiety
- try to take small steps. If you have trouble with simple interactions like when at the store, it would probably be way too much for you to randomly talk to strangers on the street, so find smaller things that seem scary to you, but where you think you could do it, like just being in public, taking public transports, asking a worker at the shop a simple question, like where is xy, and gradually learn to become more comfortable with difficult situations.
- maybe seek professional help, a psychologist maybe try medication, some things are available without a recipe from a doctor.
- avoid drugs, especially weed, this shit is the worst if you have anxiety issues.

It will take some time until things get better, but you can do it. Hope i could help.