So you think getting off the couch and incorporating a little activity into your life will extend your youth and keep your inner geezer at bay?

Seems it might, according to a study published in the latest issue of the Archives of Internal Medicine.

The study — out of King's College London — found some of what you would expect: that exercisers have lower rates of cardiovascular disease, type 2 diabetes, cancer, high blood pressure, obesity and osteoporosis. But it also suggests that being sedentary not only increases the risks of developing aging-related diseases and premature death, it may also hasten the aging process.

The researchers examined the length of telomeres in white blood cells (leukocytes). Telomeres are repeated sequences at the end of chromosomes. The researchers note that they shorten over time and may be a marker of biological age.

Sedentary people in the study had shorter leukocyte telomeres than did people who were more physically active.

You want to look old? Spend your spare time on the couch.

In an accompanying editorial, the Journal called for more research to determine conclusively whether there is a direct link between aging and physical activity.

If that's got you feeling down, you might be middle-aged. Another study has found that no matter where you go in the world, misery plagues middle-aged folks far more than the young and old, perhaps explaining why generations of the formerly care-free wake up one day and shriek when they look in a mirror and see either their father or mother looking back.

The study's authors — University of Warwick economist Andrew Oswald and Dartmouth College professor David Branchflower — says signs of mid-life depression do not depend on having young children in the house, divorce or by changes in jobs or income.

They found that most people begin to emerge from their low point in their 50s and that the ability to bounce back may come from something deep inside humans — perhaps an ability to learn to adapt to strengths and weaknesses.

Make it to 70, the authors write, and if you're still physically fit and healthy, you will be as "happy and mentally healthy as a 20-year-old."

And if you took the advice of the previous study and spurned the sedentary life in favour of a moderately active one, you might look more like someone who's fit, youngish and happy instead of someone who'd prefer to spend their time perched on a front porch rocking chair complaining full-time about the government.