Sick leave is quite boring because you don't have any strength to do anything. It is better to spend one's time indoors just recovering from illness. Usually, when I am on sick leave (luckily rarely) I just sleep and watch TV.
However, I wonder how boring sick leave was about 30 years ago when there was no such thing as Netflix, Viaplay, 75" UHD televisions or even iPhones. How people entertain him/herself on sick leave when there was absolutely nothing consumer electronics. Especially then, where you spent whole work day alone due sick leave.