Monday is a great day. A great start to the week and only a portion of the time you have until this week is over. You’re never getting this week back. Don’t blame Monday for the slow start, just get started and cut your losses.
Just like you don’t want to start a day with failure by hitting the “snooze” button, don’t start a week with failure by blaming the “Monday Blues” or whatever boogieman or the slow start.