In almost every book or article on aging, one idea continues to be stressed: longevity is desirable if accompanied by a life of high quality. But, I continue to ask, what makes for such a good life? Most of us want love, meaningful work, safety and security, energy and health, and to varying degrees, power, fame, freedom and wealth, and we want to live in a society that supports these goals.

How can we measure quality of life? There is no simple answer. It is an amorphous concept, constantly changing with the historical period and one’s culture, personal background, stage of life, and socioeconomic status. A person’s definition of quality of life is and should be highly individualized and objective.

Danger lies in a sector of society attempting to quantify, qualify or create a cut-and-dried definition of what constitutes quality of life.

Neither governments nor medical personnel should be given the authority to determine for an individual the point at which quality of life is so diminished as to make life itself undesirable or unnecessary.

For example, care must be taken when making assumptions about how older people perceive their lives. A popularly held view is that old people who seem no longer able to enjoy life may not wish to live. To an objective eye, their lives may seem so limited as to appear pointless, but to the individual living that life, each remaining day, week or year is often precious.

Longevity itself may entail quality of life and provide choices and opportunities for happiness. In fact, evidence exists that old people may prefer a longer life with illness, to a shorter life of higher quality.

Can a higher quality of life in and of itself extend the length of life? Having goals, passion, positive emotions, purpose and structure in one’s life have been associated with longevity. Length of life and quality of life are certainly intertwined.

Medicines and surgeries have done much to advance life’s quality. Outpatient cataract surgery and hip replacement are excellent examples of that.

Perhaps the classic and simplest equivalent of quality of life is happiness, which is usually regarded as being a result of one’s own doing and of one’s circumstances.

Losses and trauma can have profound effects on an individual and lead to clinical depression despite the set-point. On the other hand, a behavioral geneticist would propose that a steady diet of “simple pleasures” will keep one above one’s set-point.

One final thought is how you spend time. Time is that irreplaceable resource that must be spent most wisely, which is so difficult to achieve.