Does anyone know a good way to kill time?

It was raining all day long today. I was staying at home and watching YouTube videos most of the time. Actually I had a heavy headache so I didn't feel like doing anything...though studied about programming in the afternoon.

I really want to know how to make my holiday productive. How do other people kill time? If someone knows a good way or something, please let me know that!:) Just feel free to make any comments.