The creator of the Real Age Calculator says:
Your health, lifestyle, and habits have a dramatic affect on your lifespan. We know smoking robs a person of several years of his life, as do many other activities. It is also well documented that stress, sleep habits, and dieting can affect ones life. A 30 year old man who smokes, is highly stressed, sleeps 5 hours per night, and is overweight could be in equivalent health to a 38 year old man who does not share these conditions. This is called Real Age or Health Age. There are far more conditions that affect age than can be listed here. This test is for entertainment only. If you are concerned about the results please see a doctor.
Answer some questions and see what your "real age" could be.
Link - via The Presurfer