To quote my business math teacher, "Is the head of the department going to come tell you to put your calculator up or they are going to dock your pay."
Not talking down to you by any means - just saying don't let that stop you from doing something you might want to do.
I feel your pain about ADHD and sitting at a desk - It is killing me. I am so bored with it and cannot keep my mind on the task at hand anymore (which should be making money, but actually ends up chatting on this board for some variety).
A PA would be a great job. They are going to be in high demand in the coming years. I just don't want to be in the medical field anymore or I would do that. I always wanted to be a doctor, but alas I fell in love at 15 and got pregnant and had a baby and had to give up a lot of what I wanted. Started nursing school at one point, and ended up transcribing and have been doing it now for almost 17 years. It has been good to me, but it is time to put it to rest!