I am very similar to you. Extreme willpower and consistency. Try to isolate yourself from other distractions - I'm not sure where you practice, but for me, even though I have my own piano, I go to my University's practice rooms for this purpose. At first it was almost impossible for me to focus on practicing, exactly like you I would simply get distracted by doing the fun stuff that didn't require focusing my brain. However my desire to improve eventually motivated me force myself to practice and eventually (painstakingly slowly) it stops becoming hard and becomes fun. I'm afraid there's no short cut.
That said, try to think about what exactly it is that is stopping you from enjoying practicing and losing focus. Think about different ways to practice rather than simply bashing your head against the wall and becoming frustration. Try to understand the problems in a different way. It also entirely depends on what your reason is for practicing - why are you playing, what is your end goal?