I struggle with functionality too, so I'm going to share what's been helping me lately.
For reading or other time consuming tasks try setting a timer, it doesn't have to be a long one. If I'm wanting to read and just CAN'T sometimes setting a 20 minute timer and saying I'm going to read for that long will actually get me to read for 20 minutes instead of staring at the book willing myself to do so. You don't have to keep reading after the 20 minutes if you can't focus anymore, the idea is to slowly work up to more time if you can, and if you can't 3 days where you've read for 20 minutes adds up to an hour, and you'll have made progress in whatever you're reading.
Take a bath (if its accessible, or something you're willing to do.) For me, it helps me feel safe and less stressed just enough to actually focus. I do this a lot when I'm taking classes and read what I can of my coursework off my phone, but it works for other things as long as it's something that's accessible while my phone is in a sandwich bag to keep it from getting wet. Sometimes this also let's me send emails I've been putting off for weeks.
If you have a whiteboard or a chalkboard, write what you want to get done on it and mark it off as you accomplish it, or write things you need to remember on it. I have mine by the door so I see it regularly and it reminds me of things I've forgotten due to brain fog.
I don't know if you struggle with phone calls, but my anxiety makes them feel hellish. Try writing a script you can follow or recite what you need to say in your head before dialing the number. Do this for as long as you need. It's ok if you stumble over words, I get the impression most people answering calls for work are used to it. They can tell you're anxious but in my experience they're pretty understanding.
It sounds silly, but congratulate yourself for getting something done, even if it's small. Sometimes I have to celebrate making an important phone call or washing the dishes. Acknowledging that you've done SOMETHING rather than being frustrated that you haven't done anything can help with motivation to get something else done. Sorry this is so long, but I hope at least part of it helps.