Absolutely. What we teach can be done by people whether they're healthy or sick, old or young. Theravadin Buddhism, the way that we teach, is very much down to earth. Its practices are not anything weird. It's very practical. If you're sick, one advantage for a lot of sick people is that they simply have to move slower. That's what happened for me when I had my back injury. It's actually an advantage in the mindfulness practice to be sick. Sounds terrible, doesn't it? But one teacher in particular said, "Walk around here, practice around here, as if you're 85." He actually wanted people to walk so slowly and so mindfully to actually raise their level of awareness in the practice. From what I've seen with my parents and others, 85-year-old people walk slowly. They're looking down at the ground a lot. They're very careful because they're afraid of falling. So they actually have to be more mindful.
Now, as to the reflection side of the practice, older people have seen life more than the rest of us; they have more to reflect on. They can reflect more about death and impermanence. They can use that reflection in a wise way to develop more inner happiness. For sick people, one of the best reflections to use is "how fortunate you still are." Your body's falling apart, maybe you've been throwing up, maybe you've had lots of diarrhea, you have a fever -- are you still fortunate, though? Do you still actually have a nice home? You still have some friends, you still have money, you still have the Buddha's teachings, even if you're sick. Yes, so even if you're sick, you can definitely use these reflections and, sick or old, it can benefit you.