I'm always interested to see that those who exercise regularly work from 9am, or 'do the school run', so presumably work after 9.30am or later
I'm sure that's the case for some people, but not in my experience. My work hours vary, and on the days I'm working from 7am/7.30am and not doing the school run, it's far easier to exercise first as I only have myself to worry about. All I have to do is get up earlier.
Whereas on the days I'm doing the school run it means I'm up first thing and out for a run, then back for 8am at the latest to sort kids, take them to school, then work starts 9am.
The easiest work/exercise scenario I've ever had is when my office was 6 miles away from home and I usually started at 7am. I could get up, run to work, shower there, and be at my desk ready to go. But again, that meant leaving the morning kid stuff to DH.
I also spent a few years cycling to work and running at lunchtimes, which was an easy way to fit everything in around kids.