Without discipline, it's so hard to make progress it seems. And I really want to make progress... so why can't I really have discipline?

I see myself in Berklee a year from now. I really do. But at the same time I wonder whether I'll really make it because I keep disappointing myself; with my lack of discipline to sit down and work on my theory, with my basic ability to grasp the theory, with my lack of desire to sit and practice for hours sometimes, with the general absence of inspiration. <<
Somehow I think I was expecting all of the above to just disappear once I made up my mind about what I want to do and starting working towards it... So what does that make me? A lazy arse? I suppose... scatterbrained too, I guess. I just can't seem to let go of distractions. -sighs-

I go on hiatus on my favourite site to concentrate on my studies and I discover social media... and still keep doing graphics. Honestly.
Then, I get too exasperated with myself and go into depression. Then I work hard to remind myself of what I'm working towards and I start focusing again; I go into a happier state of mind and I'm back to wasting my time. WTF. <<

WHAT'S WRONG? WHAT DO I NEED? HOW CAN I FIX THIS?