How old are you? Before you answer with a number, think about the different ways that age can be perceived. Certainly one way to mark our time on Earth is to count the number of years since our birth. But some experts on aging say that there are many different types of age, depending on a variety of factors.

Researchers at the Sloan Center for Aging & Work, part of Boston College, recently released a report on the subject, titled "The Prison of Aging," according to US News. It focuses on several different types of aging, and researchers there say that together these concepts can reveal a person's true age.

In all, the report identifies 11 different concepts of aging. The first, "chronological age," is the one with which most are familiar. The others may be less well known, but are still worth considering when thinking about aging.

"Physical-cognitive" age concerns your physical ability. While some people in their 50s and 60s may feel out of shape, others are able to exercise regularly, and even enjoy doing so.

Other perspectives on aging include the "career stage" or occupational age, which is figured in terms of one's career path, professional abilities, and competencies. This relates to another tenet of the report, "tenure."

Have you ever met someone you'd describe as "young at heart?" Then this person may have a higher chronological age, but a younger socioemotional age, which refers to human maturation. Social age is similar - its the age at which others perceive a person to be.

But what happens when a person's socioemotional age clashes with their perceived social age? This may be a very common phenomenon among baby boomers, who truly embraced their youth, but now find themselves on the other end of the aging spectrum.

Statistics show that a full 28 percent of plastic surgery patients last year were between the ages of 51 and 64 last year, according to the American Society of Aesthetic Plastic Surgery. Another 8 percent of surgeries went to individuals over the age of 65.

Baby boomers have lived longer and spent more years working than generations before them, and have helped bolster acceptance of plastic surgery across the country. According to BabyBoomers.com, many members of the generation are physically fit and eat well, which makes them suitable candidates for a number of procedures.