A girl would distract you even more from any useful and/or creative work, believe me, sigh...
The motivation is the art itself, not the result. If you want porn, there's more than you can digest, ready-made like pet food. Draw what you love to motivate yourself but that is not the motivation. Nobody draws because he loves, say, landscapes that much, but because he loves painting, watercolour, oil, that much.
What motivates me into action is to have the internet as forum. I already said that recently here in a thread about feedback. But also important is the option to share sketches, unfinished things, that makes me work every day, practicing, experimenting.
I am finally about to branch out to other subject, more sane, mainstream comic stuff. There are great art boards where the pros hang out (sorry, have to find yourself) and you better be good to post something there.
So trash your TV (I don't have one), draw something every day and don't just copy porn, study the basics, anatomy, colours, story-telling, light, abstraction, styles. Am I already boring you
School doesn't count, wait how much time you'll have when you hit a tough job.
Regards, TT