Seek out something you haven't done. A lot things are quite easy, cheap and probably something you've wanted to do for a while. If you have an instrument around the house, maybe now is the time to learn it. If you've heard about a good author, now is the time to get a book (try your library). My last holidays I spent hiring out classic movies that I've heard of, or heard quoted, but never seen. Go on the cheap day and you get hours of some of the best entertainment in history for a pittance.
Alternatively try a skill like woodwork, if you have a few tools around the house. Simple mechanical projects like a mouse-trap racer, paddle boat, or a crossbow or catapult are really rewarding little things to make. They get you thinking creatively, and you practice a valuable skill.
If you really are bored around the house, then a team sport is probably the best way to go. Training will get you out of the house and meeting new people, and the competition should get rid of most of your extra energy. Hit your parents up and see if they'll pay for it, most parents like seeing their kids do some sports.
Think about what you would like to have done, and then do it. It makes life interesting.