Mondays are 1/5 or more of your work life depending upon how much you work. They can be the most productive day. Mondays and Fridays tend to be my most productive days because I want to either get going on stuff or wrap stuff up. So both motivate me in different ways.
I manage hundreds of Social Security Disability cases and dozens of PI/WC cases. In other words, I have to be thinking months and years ahead. There are always issues of medical records, liens, and a myriad of deadlines.
Those who hate Mondays are at a disadvantage. I don't love them, but I view them as a chance to start the week off on a good note.