Gay wizards

Ok. So... writing is hard, i get it! But i wonder how the other writers, the real writers do it, how they stay focused and write several pages a day. The problem with my book is that i don't know how to continue my storyline at the moment and i'm not sure about the ending just yet. So.. yes i could write several pages a day, i sometimes do, but oftentimes there's no real point in doing so. I am stalling and the reader will smell it!

But the thing is.. i don't wanna become one of those writers whose stalling becomes part of the book description. I want the main threads to fit together nicely before i think up the boring stuff to fill in the gaps.

How do i do that?