We have amazing self control, unless it's about our interests.
Mental addictions to INTP's is more like. This is fun, I want to spend my time doing this. If I don't, I'll be bored while I think about doing it anyway.
It can be a problem for some, you obviously have to make some priorities to not let your life suffer under your interests too much.
I mean, I could do the things I want to do 18 hours a day and 6 hours a sleep, and never tire.
We obsess with our interests.
We can only apply self control on our interests when we realize the amount of time we spend on our interests is too much and will eventually result in collapse. And then we can work on controlling our interests.
Hardest for me was going from rebellious, freedom student soul, to fulltime worker boy. I just couldn't concentrate on my work. At work I was thinking about things I would do after work, all day long, every day. I really had to work on that since work suffered under it at first. Nowadays, I can seperate the two perfectly fine. I can be totally obsessed with something in one moment and *snap* suddenly place it away and do something I am supposed to do, without leaving my mind with the obsession.
I never had much problems being a student, because the stuff I picked up on classes was enough for me to get passing grades in general, and I never had to study hard for anything. And could always find the time to read the material before going to sleep prior to tests and such.
So ehm, maturing and training. 's all you can do!