D. G. Myers writes a very frank article, The Mercy of Sickness before Death, about some aspects of his experience of end stage metastatic prostate cancer.
You may, for instance, become more conscious of time. What once might have seemed like wastes of time—a solitaire game, a television show you would never have admitted to watching, the idle poking around for useless information—may become unexpected sources of joy, the low-key celebrations of being alive. The difference is that when you are conscious of choosing how to spend your time, and when you discover that you enjoy your choices, they take on a meaning they could never have had before.
I recommend the article highly. I was struck by the strong differences between the experience of terminal illness and chronic illness — the relationship to time for example.