If you could look into the future wouldn't you want to know exactly how long you had left on this earth – and, if it wasn't great news, take some steps to change that.
Well, while we haven't got a crystal ball or psychic powers, we do have eight easy questions that can help you pinpoint if your body is ageing faster or slower than it should, which might give you some clues.
1. Do you exercise for between 100 minutes and six hours a week?
Then congratulations, your body is five to 10 years younger than someone who works out for less time – or even a lot more. This might surprise you as we often think the more exercise the better but when experts studied the length of telomeres they found they were longest in those just doing moderate amounts of exercise. Telomeres are markers of ageing within our cells – as we age they usually shorten, so the longer they are the 'younger' we are biologically.
"We think that more strenuous exercise done for long periods of time might stimulate negative responses in cells that require longer recovery and repair times," says Professor Stephen Roth from the US's University of Maryland. Aim for 30 minutes of moderate exercise most days of the week.
2. How many trees are on the road you live on?
If the answer is 10 or more, you're likely to feel seven years younger than those who don't live somewhere so green (and your risk of heart problems falls to that of someone 1.4 years younger).
"Maybe people in tree-lined areas walk more or the results could be driven by air quality," says study author Marc Berman from the University of Chicago.
Whatever the reason, green is good so aim to get close to nature as often as possible – and, if you don't live in a green area, head to the park at lunchtime to get your daily dose.
Living near the beach can also improve your wellbeing – UK researchers found living less than 5km from the sea gave both a physical and mental health boost.
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3. Do people say you look good for your age?
Then you might be younger on the inside too as work published in The Journal of Gerontology found people who looked at least two years younger than their true age also had a lower risk of high blood pressure.
This is good news as experts estimated having blood pressure over 140/90 increases your biological age by six to 10 years.
"Having high blood pressure means that your body is working harder to pump blood and oxygen through your body," explains Priceline pharmacist Edward Tanzil.
"The optimal blood pressure reading for a healthy adult is 120/80. I'd recommend that everyone over 40 should get theirs checked every six months – if you're younger have it done once a year."
4. How’s your cholesterol?
Fifteen per cent of Australians aged 35 to 44 have high cholesterol and the incidence rises by about 5 per cent per decade, according to the Priceline Health Tracker survey. This is bad news for your biological age as high cholesterol can increase it by 3.7 years.
"The main risk factors in developing high cholesterol include a diet high in fats, sugars and cholesterol, and having a sedentary lifestyle," says Edward Tanzil.
If you don't know your cholesterol level, it's easy to get it checked. "It's now possible to do on-the-spot cholesterol checks in the pharmacy which only take two minutes to complete," says Tanzil.
5. Are you good at controlling stress?
Interestingly, when it comes to premature ageing it's not so much the amount of stress we go through, but how much it gets to us that counts. In research from the University of California those who had the highest levels of perceived stress were 10 years older biologically.
"You experience the greatest degree of stress when you feel out of control," says Perth-based corporate health advisor Dr Linda Friedland.
"When you become aware of feeling stressed, don't rush into frantic problem-solving mode, instead slow down what you're doing by 25 per cent. As you slow your pace you'll feel the stress start to lift and you'll be able to work on tackling things."
WATCH 19 ways to reduce stress. Article continues after video...
6. Are you still a smoker?
Smoking adds eight years to your biological age, but do you know how many years quitting can give you back? According to research from the UK's University of Oxford, if you stop smoking at 30 you add 10 years to your life, and quitting at 40 gains you nine years, while a 50-year-old stubbing out the habit adds six years to their lifespan.
"It's never too late to stop," says Natalie Clays from quit smoking specialists Allen Carr.
"When you do, don't think of quitting as 'giving up' smoking. It implies making a sacrifice, or losing something precious – what you're doing is gaining your life back."
7. Do you enjoy sugary drinks?
Consume 560ml of sugary soft drinks daily and you're almost five years older biologically than someone quenching their thirst with water, say researchers from The University of California San Francisco. Even if you only have 225ml, you're 1.9 years older.
"A high-sugar diet causes cellular ageing," says nutritionist Michele Chevalley Hedge, author of Beating Sugar Addiction for Dummies.
"You don't have to just drink water, though – try sparkling water with slices of lemon or lime, or teas like cinnamon, liquorice or ginger particularly help satisfy sugar cravings."
8. Do you eat at least five portions of fruit and vegetables daily?
Then you can add three years to your lifespan, says analysis from Sweden's Karolinska Institute. If you're not a fan, try this tip from personal trainer Alison Cavill from Fit Fantastic: "Try plate layering. Before you put anything else on your plate, chop or grate veggies like lettuce, spinach, kale and carrot then place the rest of your dinner on top."
Not only will this see you eating more vegetables, adding the food on top disguises the taste of any you're not so keen on.