@tophatfox The trick to white collar work is to preserve your soul while doing it. When you're done with the office job you'll have plenty of money...just make sure you don't lose yourself along the way.
When I was in a high-stress sales job I was having difficulty focusing on the more mundane aspects-grinding out spreadsheets, hours of reading technical papers, etc.
A friend gave me a pill of adderal or similar, and I had an incredibly productive day. After asking around I found that adderall was incredibly common on the sales floor; everybody between 25 and 32 who was any good seemed to be taking it.
I went to a psychiatrist and explained the issue. She asked me if I had trouble concentrating when I was young (no), and if I had trouble studying in college (again, no), and if I was currently stressed out (yes). She diagnosed me with depression and said that the concentration issues were symptoms.
When I switched jobs at the end of the year my symptoms went away and I regained my ability to concentrate for long periods of time.
TL;DR Adult onset of ADHD was just stress and depression. Changing jobs fixed the issue, and was a healthier option for me.