If I had my personal feelings attached to my teaching work I think a lot of my students would be leaving the lessons crying, or at least physically beaten

I simply look at the lessons ON THAT DAY, I don't listen to excuses for not practicing, I just say play and dont talk about why you can't play. We deal with what we have even if what you have is in tatters. I try to be happy about it and say, well if you had no problems you wouldn't need me. Although inside im thinking... damn it this is the 3rd week we are doing the same damn thing. I am always acting as a source for inspiration to the student even when I don't feel like it.
It is one of my pet peeves is students trying to explain why they don't practice. I make all my students feel like they have to show me next week an improvement, I do that always by encouraging them and showing them how to practice, all they need to do is invest time. So they all know if they don't progress it's their fault because in the lessons they progress and they know how to make further progress themselves, they just haven't the disipline to do it themselves. I say to all students at least once; Look I really don't care why you didn't practice so don't bother explaining it, I do not feel bad if you don't practice, but I feel happy when you do practice. Sometimes they must tell me to get the stress off their back for not practicing

I try not to let them explain themselves and simply play. I find if you let students explain why they don't practice they will continue not to practice cos they know they can explain their way around it to you and feel better. Simply don't listen to it and say, just play, let the music do the talking.
I have one student who always says "Im tired" ALL the time without fail every lesson! I can't do this because im tired, I can't practice cos im tired etc etc. If we repeat something more than 3 times we starts feeling tired and lazy. I gave him prelim music (and hes grade 5 at least) and he still didn't do the work. I tell him why bother doing piano if you don't practice, he says he likes piano, the parents say, we don't care if he doesn't practice so long he has lessons every week. Wow, thats totally against my thinking, but it works for them, not that i enjoy the snail speed (for the last 4 years). I think they are thinking on the lines of; it's better to do very little instead of nothing, which is true, but not without taxing alot of my patience.
I have been saying "IM TIRED" back to him when I know hes about to say those lovely words

The lesson has become the "I'm tired" lesson to me, I find it a good lesson for me to learn how to keep a student awake, I am constantly prompting his attention and pushing him to repeat, Keep the ball rolling. Ill be like... COME ON, a few more repeats and you got it, don't stop now the balls rolling, keep going!! I try to sound excited, I treat the lesson not as a music lessons for me but more of a teaching lesson, how do you keep a student awake and push them on to learn. It's really like the trainers on that show The Biggest Loser. They push the lazy excersising on and on and on and on don't give anyone a break, and when they complain you ignore and push them harder. I mean my lesson with this boy is only 30 minutes, so its not like he's being tortured by my intensity to keep him awake.
I believe every students needs to be pushed with different intensities, So i dont mind being wtih students who don't practice. I find it a big challenge for myself to make them progress, and I have seen more lazy students become efficeint learners with my pig headed persistience and honest looking excitement with their progress. I have learnt to accept snail speed progress and I am not worried about it one bit so long I know for sure it is because of their lack of time to practice, not lack of practice method.
I like to get to the bottom of things sometimes. I have discarded a lot of students after asking them why they are learning music for. When they shrug or say, parents are making them do it I will always drop the student soon after if the attitude doesn't change (and this has happened only 3 times in the last decade). The core reason for learning music must always be known, if the student hasn't a reason to learn they will not invest time and thus you will have to deal with either no progress or apathetic attitude to learning, which I think is just not worth the money.
I remember reading somewhere that a music teacher is one of the most stressful job you can do.