Can anxiety cause severe weakness?

Aaaaabsolutely!!! Think of your body like an engine. When we're relaxed, our engine is off. When we're a little tense, our engine is in idle. Severe anxiety is like our engine revving in high gear! Not even the best car can handle that 24/7! I know it sounds impossible, but do anything at all that helps you relax. I listen to stand up comedy, or bon Iver, or draw. Sometimes listening to rain or deep bass sounds help me calm down. But nothing helps as much as deep breathing exercises. I know! I know man.. I laughed at that suggestion for decades! But it fr is like a natural high. https://youtu.be/tEmt1Znux58 Dunno if links work on here or if you can copy and paste.. but if it doesn't work, youtube box breathing. The trick is to breathe softly and slowly in through your nose, then forcefully but slowly out through your mouth. Press your tongue to the roof of your mouth while you do it and let the air flow around the sides. I don't know why this works, but you'll get super duper calm and light headed after about 5 or 6 of these. It's very euphoric after it starts working. I wish I had believed that about 1 billion anxiety attacks ago.