I’ll try and keep my answer brief, because I feel the urge to infodump lol.

1. Task anxiety: I struggle with this and am under treatment for it. For me it has 2 parts: 1. Something like “see the dentist” that most people see as 1 step, I see as all the individual parts (like a previous comment lists) and get overwhelmed by it all and feel like I have to get it all done at once. For this, it helps me to write every single step down and just try tackling one when I feel the motivation.

2. My brain jumps ahead to thinking about worst-case what ifs, like really expensive dental work. It helps me some to ask myself the best and worst case for this, and I keep a list of examples when I expected the worst and it didn’t happen to remind myself it’s not guaranteed to be the worst case.

3. Future/jobs and career: First of all, don’t believe what people have told you about your intelligence. Everyone has areas of expertise and areas of weakness. If math isn’t your thing, there are plenty of jobs where you don’t have to do math (or nothing harder than add, subtract, multiply, divide). How you did in school and not getting your GED (yet) doesn’t imply intelligence. Second, don’t feel like you have to choose the career that you’ll do for the rest of your life. I’m on my 4th “career” and none of them are what I initially studied in college. In true ADHD fashion, each time I’ve sort of fallen into a new opportunity, my passion (about the novelty) got me the job, I dove in for a while, and then it fizzled out and I chased another interest.

Most important is to not get hung up on some image of what you “should” do. See if you are capable of improving yourself for 15 minutes per day, exact, with a stopwatch.

A first 15 minute session might just be a best effort of assembling study material.

Then see how it goes: Can you learn something new during that time? If so, you can do it, and it’s just a matter of time.

What motivates me is that after those 15 minutes I’ll be smarter than I have ever been before. You can also do 25 minutes if you feel it.

I have done great at times, long ago, to study something new. Most times it didn’t work out, though. One of my most toxic thoughts is: I should basically know this and it shouldn’t take long, I’ll just skim through the material. No, real progress happens when I set aside a brief moment to learn just this one little basic thing, but for real, with taking notes, practising if applicable. Turn that into a daily habit, and it’s really powerful.

Anxiety over doing something can really kick you down and lead to deep depression and feelings of incompetence. You can do it. For me I just look for a little goal and that helps me tackle the bigger ones. If I’m in a rut I will clean my home or go exercise, anything I can basically do on autopilot that’s an easy win.

You absolutely can get your GED. You can pass it. Once you get thru that block it may change your feelings about your future and what you hope from it. Just taking some elective classes at a community college can lead to new interests and meet new people. It’s just easier to have someone like a teacher push milestones for me to reach instead of relying on my own motivation to do it.

What you describe - that feeling when you think of doing those things, my personal experience has me classify it as overthinking becomes getting overwhelmed. And once I’m overwhelmed, I want to escape.

Keeping in mind coping mechanisms aren’t one size fits all, the coping mechanism that helped me is to write out the problem step by step. This forces me to think slower, and helps me get out of that recursion of thinking about the same things.

I’ve also found some success in the age of AI LLMs asking one to break it down as well.

An example would be the dentist. First I need to find one, I need to look at reviews, I need to make sure they accept my insurance, I need to make sure they’re reasonably close by. Alright, I compile a list of a few options, now the next part is the hard part: I have to actually call to get scheduled. But once I have it scheduled, my social anxiety is superceded by my desire to just get it over with. Sure I may feel that anxiety once I get close to the appointment, but I can cope with that - the real trick is by breaking down the process I didn’t get overwhelmed as quick, and if I did I had notes to come back to.

It is normal to be anxious about things sometimes. I also didn’t have my GED and had dental issues and felt less than because of it. The dread I’d feel having to go through the testing or the cost of fixing my teeth made me not want to go through either. I did eventually do both, after basically giving myself an ultimatum. I was depressed and didn’t feel like existing as well, but there were a few people that I really didn’t want to let down. The place by me that let me obtain my GED has a process where they would test your knowledge, then tutor you on your gaps, then let you take the tests. I ended up passing with pretty high scores because I over prepared, which felt really nice. That gave me enough confidence to get my teeth fixed and worry about the cost later, which also boosted my confidence. The anxiety didn’t go away entirely, but I remember the feeling of overcoming what I thought were impossible tasks. That was over a decade ago. I’ve since gotten a good career and I’m currently the most confident I’ve been. I don’t know if my story will help you, but maybe you knowing you aren’t alone in that feeling can offer some solace. My only advice would be to not let the anxiety control you. It’s not a switch you can just turn off, but maybe by tricking your brain by remembering failing won’t hurt/kill you, you can overcome yours.