Different people react differently to flu and different strains are different. I remember when I was 30 I got the flu and I had enough energy to walk to the nearest convenience store to get lunch and enough energy to do an hour of driving practice a day and the rest of the time I lay in bed. I did not have the energy to read a book. I didn’t have the motivation to turn on the radio. It was awful. Glad I haven’t had the flu since.