How to warm up my mind for writing?

I'm 17. It's been a year since I've last practised writing. I love writing different kinds of compositions; articles, stories, poetry. Currently I feel my head is not helping. How can I warm up my mind to start writing again? I'm planning to write a book and I'm so excited yet helpless.

Answer: 
I'm 17, as well ^_^ In what area of writing are you currently at loss over? Is it plotting and creating a story or actual writing? For coming up with plots, characters, and various other fun necessities, I highly recommend visiting ❧ TVTropes ~ http://tvtropes.org/pmwiki/pmwiki.php/Main/Tropes NanoWrimo Adoption Society ~ http://www.nanowrimo.org/en/forums/adoption-society If your writing feels stilted or awkward, I suggest picking up a novel -- preferably one with the style and voice you wish to mimic -- and spending the day finishing it. After being exposed to well-formed prose and soaking up the writer's language, your mind will most certainly start formulating pieces of dialogue and you'll start to subconsciously weave vocabulary to create beautiful sentences which begin to flow with the rhythm of the scene -- even if you're not particularly sure of what you're writing. Good luck and have fun!