I've scheduled my second knee replacement surgery in September. That way, I should be through with physical therapy by the first of the year (not knowing what to expect from US health care changes).
Our elderly cat, at least 15 years old, has lost about 2/3 of his weight, has kidney disease and a heart murmur. He's eating high calorie "critical care" canned cat food, takes a pill for the heart murmur, and still enjoys walking around in the yard and lying in the sunshine and shade. We won't have him much longer, but I hope he can enjoy life as long as possible. We'll know when it's time.