As a fellow-teacher, I would have to say: relate it to their lives. Now that is tough when it comes to grammar. In that case, I would emphasize the "reward" aspect by learning the grammar rules now: the Cadilac they will be able to buy because of the great job they will get in the future. In other words, build up some dreams. (I am currently doing this with a college class whose vocabulary is pedestrian - "the job interviewer will hire you because he can see, by the vocab you use, that you are mature and intelligent"). Often, you have to "trick" the students into buying into your program. Also, if you treat it (in this case, grammar) with awe and reverence, they will pick up your intensity. It's like grammar is the Messiah arrived on earth, it's that earthshaking. So, I'm talking about attitude (your attitude) rather than the content that you have to teach.
As far as writing, again, I would at this stage relate assignments to their past, current, and future (hopes, aspirations, goals). If you connect it to the events in their lives, and give them praise whatever they write, it will click. Essay question: "Have you ever known a Kate? a what's his name, the burly guy? Yea, Petrucio. Are you a Kate or a Petrucio?, etc.
