Having never knowingly had a flu-like disease (at least as an adult)
A real case of influenza is horrible.
I have had one perhaps something less than once a decade in my adult life, and for about 2-3 days you almost feel like death would be a relief from the whole-body pain, headaches, nausea, alternating fever and chills and other symptoms that cannot be medicated or soothed away. Then another 3-4 days of feeling better but still really bad on the order of a severe cold.
And then you wake up one morning with the disease over and you feel like a whole new person and can't wait to get back to life as usual.