No matter how boring the exercise you are teaching is, no matter how boring the student is. Rememeber back to your initial days of learning and try to be the instructor you wished you had.
It is sometimes very hard once the flying gets boring and you loose interest to give 100%. But you need to keep up the enthusiasm for the student as we easily forget that they have worked and saved hard for each flight, and this may be their dream come true. How we are in their flying instruction often shapes the way they feel about flying forever.
Have seen students walking away from a lesson looking depressed as they have recieved a right mouthfull from a disgruntled instructor who wished he was in a jet really. And the student has never flown again, as what he has wanted to do for years has now become something he/she dreads every weekend.
Not technical information I know, but worth thinking about...The personal skills...