To play an instrument could be a profession, or just a moment of relax in your day.
A moment when you release your stress and your tension accumulated during the day.
It is a moment of creativity, when you let your soul come out.
You don't need to be Beethoven in order to do that, just let yourself go free and see what comes out.
Anyway try to do that in your room and with a low volume level, otherwise your neighbours won't be to happy! OK, so what instrument to choose, if you haven't yet? Well the guitar is a great one for various reasons:

• versatility: you can choose the electric, the acoustic, the classic;
• cost: you can find very cheap guitars, they are not the best, but they are OK to start with;
• learning options: there are literally tons of books, videos, tutorials on the topics;
• dimensions: it is a small instrument, it is a light one, so you can transport it very easily and you can bring it to the beach to play with your friends;

It is important, anyway, to start with the right foot! So I do recommend:

• find a good teacher: it will avoid you a lot of mistakes, especially at the beginning;
• don't buy the cheapest you find on the store to save money: after a while you will realize that it was the cheapest for a good reason...
  it was a crap.
  So, maybe, ask a suggestion to your new teacher to choose the first guitar;
• commitment: if you want to get to a level of playing where you can actually enjoy it, you'll need to do a bit of practice, everyday, at least for 15 minutes;

So, my friend, good luck with your new career, maybe you'll be the next Jimi Hendrix!