Perfectionism, Procrastination, Stress, and taking deep breaths
You might be a perfectionist and think people would judge you for your work, so much so you don't even want to start it because you know it won't be perfect.
Try to embrace imperfection. Start doing the task at hand for 5 minutes and feel the discomfort (the pressure in the chest, the heat, the sweating, the lack of air), that's your body saying "This is bad I don't want to do it" because you think the outcome won't be perfect; when that happens, take a deep breath, tell your self "This is ok, I'm not in danger" (that chest pressure is you body reaction to danger) and count to four, then if you can, try keep working for another 5 minutes and repeat. Eventually you'll teach your body that that's ok, you're not in danger, you don't need to do a perfect job, a good job is enough and people won't judge you for it. Even if you do a bad job that's ok too, mistakes are can be used for learning.
Stress is a natural reaction to danger, for a time when we used to live in the wild and be chased by predators. Modern life doesn't have predators but our body doesn't know that and still generates stress for other reasons, like having to do desk work. In the wild stress would get you the energy needed to run away from the predators and this would release the stress, but in modern life there's no predators and that stress intoxicates you. Your body reaction is to avoid that source of stress. You might not even want to get out of bed because, what are you going to do next? brush your teeth, and then what?, oh no, you have to work -> stress!!!. By the way not all stress is bad, but that's a different topic.
Some exercise and sunlight helps release the stress too. Mental therapy helps to understand these things as well and gives you more tools, but you need more than one session.
Good luck. I know it's hard. It won't be easy, but it won't be as hard as you think.
Original: myself here.