You need to cough those secretions out of there frequently or else you'll be stuck in the hospital for a lot longer with pneumonia.
If they say, "But I don't have to cough," I explain that the cough reflex only works to about half the lung, so they won't feel the urge to cough, but that the junk is still in there, and it needs to come out.
Sometimes I ramble on a little more, especially for post-surg ab patients, because they're usually the most reluctant to cough and get out of bed and move. I tell them that their body was never built to lie in a bed, and I explain that lying in bed can cause blood clots to the legs, keep their bowel from working (which means you get--tada!-- to keep that NG tube in for much longer), and lying in bed can also cause pneumonia.
I finish up with "Let me get you some pain meds or teach you how to use that PCA button because the things you start doing now will play a big part in how fast you get better and get out of here."
I outright woke people up. Not roughly, but in a matter of fact way. If they complained I just told them they would have plenty of time to sleep when they went home, but that the reason they were in the hospital was for me to remind them to deep breathe and cough. I also told them they'd hate me a lot more if they got pneumonia and ended up staying in the hospital longer. That's was usually enough to get them going. I also had an arsenal of jokes that I told for those who only gave a poor cough effort. You can't laugh and not cough after anesthesia. They never knew what hit them. I worked with post op thoracic surgery patients.
If a pt is groggy then I will gently tell them that I am going to be repositioning them. While changing their position I tell them to take a nice, deep cough. If the I.S. is there then I will have them use that a few times. While they are in the midst of drifting back off to sleep, I tell them the importance of the resp. exercises.
When the pt. is more awake, I more actively enforce it.
I always said - because most of ortho patients were elderly, that I NEED them to use their IS and I would watch them do it. It only would take seconds to watch and you can say you SAW them do it.
Explain the importance - and how you have seen many a patient fail to do this simple thing and end up with pneumonia. So you don't want that to happen to them, you like them Whatever you say, just make sure you mean it. I had seen patients develop pneumonia in a matter of 2 days because of lack of the TCDB and IS. It is a real possibility. So push it if you can.