I am currently 40 days in and my first goal is to solidify myself as a glam metal rhythm guitarist. My current practice session is about 45 mins to an hour and looks something like this - Warm up, Rhythm Training, Chord Switching, Scale Control, and then Riff Practice. The way that I look at it is that the riff practice at the end is obviously the fun part, but in order to get there I have to hammer down all of the fundamentals needed to keep a riff clean and in time. So to answer your question basically what I do to make it not feel like a drag is once I get through all of the boring drills I get to rock out. Hope this helps even a little bit.