Some days are worse than others and when it's bad, it can get REALLY bad. "Helpless" is the word that I often hear people use who are close to chronically or terminally ill loved ones. At times, all you can do is watch and hope for the best. At some point, those good-intentioned words of motivation and support are lost in the pain and seemingly endless suffering. Being headstrong is the only thing left for the individual when the body refuses to cooperate physically while working in tandem with your (hopefully, good and caring) doctors.
After going through some of that experience, I would say to the individual to:
1. stay reasonable, logical, and sane by way of thinking during difficult times, as tired and as frustrated as you are;
2. believe in yourself and keep your desire to live in mind;
3. know that anyone who has stopped by or even inquired about you is pulling for you and if you give up, then where is all of their energy going?;
4. let patience be on your side--the extra amount of stress on your body and mind will not get you into a better state for treatment, healing, or hope;
5. not neglect your body's needs (be it basic exercise/movement or brushing your teeth) because you will pay for it later when you recuperate (!!!);
5. reach out to god, if you believe in it.
Hopefully somewhere down the line, you arrive at a point where your health is manageable/tolerable--the ability to find a balance, where you have some good along with the bad--as I have at this time.
Best wishes and stay fighting, as others are fighting for you!