I am a physician, a pathologist, at a busy cancer hospital. I look at peoples' biopsies and give their other docs the news about what the biopsy shows.
Biggest challenge is probably interruptions; everyone needs my opinion now on so many things. Second is just the amount of work many days; the input keeps coming in, but getting to the lists to actually DO something other than the day's work is often impossible.
Ah, another challenge, home. Of course there's things that have to be done to keep the household going: chores, pay bills, fix clogged drain pipes outside, clean gutters, etc.
Another challenge for me is thinking that once it's processed on to a list, then somehow I've accomplished something and can relax. Lists grow real fast that way!