Just about every fitness guru talks about the marvellous benefits of exercise, but has anyone ever mentioned that exercise can hasten the ageing process?
Ageing is inevitable - it happens to the strongest, fittest and healthiest of us.
When it starts, reflexes are slower, coordination suffers, bones weaken, wrinkles appear, and before long, your memory starts to lapse.
The average person also gets less sleep in maturity than in youth.
Gosh, you can't even snooze in comfort when the body clock speeds up.
The ageing effects start around the age of 35 and increase rapidly after that. Many of the changes attributed to ageing are caused largely by disuse or overuse.
While genetics does play a role in the type of diseases you may get, it has very little to do with how fast or slow you age.
A great chunk of how you age is determined by how you exercise and what type of workouts you're doing.
You cannot stop the clock, but you can slow its tick.
Have you noticed how the majority of die-hard runners, endurance athletes and those who slog it out for hours in the gym daily look older than they are?
They may be fit and healthy, but most look haggard and pruned up.
"If you want to look young, don't become a marathon runner," said cosmetic physician Dr Van Park in a 2013 interview published in the Sydney Morning Herald.
"One marathon every now and then is okay, but long-term excessive exercise can hasten ageing. Just look at the faces of regular marathon runners."
This could be the knock-on effect of putting your body under extreme stress by doing lengthy exercises.
"Cortisol is released when we're highly stressed, and high levels can lead to depression, memory loss, abdominal weight gain, insomnia and premature ageing.
"We are not 100 per cent sure of the effects on collagen, but we suspect increased cortisol breaks down collagen and elastin, which fast-tracks ageing.
"Add to that free radical damage, ongoing sun exposure and a high-protein diet, which often goes with excessive exercise, and men and women who exercise intensely over a long period do age faster," Dr Park said.
According to Shin Ohtake, fitness and fat loss expert, and author of MAX Workouts, you need to discover how to trigger your youth-enhancing hormones to slough away old, dead cells, while elevating your metabolic process so you can burn away stubborn, flabby fat and replace it with lean, toned muscle.
And endless cardio is definitely not the answer.
Pounding on the pavement or treadmill for hours doesn't do your body much good.
"Metabolic training involves doing certain types of exercises that involve your entire body, so you can activate as many muscles as you can in a short amount of time.
"It's completely different from doing traditional isolated body-building exercises (like biceps curls or leg curls) where you're only using one muscle at a time.
"This form of exercise takes way too long and doesn't stimulate enough muscle fibres to increase your fat-burning and youth-enhancing hormones," he writes.
The more muscles you're able to activate at the same time, the more you'll be able to trigger your youth-enhancing hormones.
An example would be to perform compound exercises, which utilise multiple joints.
This means maximal muscle recruitment, high nervous system activation and more stimuli for growth. So, lifting weights or strength training is a must.
Busting your stress on the bike or taking a kickboxing class might make you feel better instantaneously, but the feeling doesn't last beyond a few hours.
When you exercise, your body releases a hormone called endorphin within 30 minutes.
This feel-good hormone interacts with the receptors in the brain and triggers a positive feeling in the body.
But when you overstress the body, you no longer feel euphoric afterwards.
In fact, sometimes you might feel nauseated, or even throw up - I know I've experienced this!
Really, all you need is about 30-40 minutes of exercise four times a week, which explains why workouts like High Intensity Interval Training are popular, because you only need to do them twice a week, and add on another two days of strength training and yoga.
Studies have shown that incorporating yoga into your fitness routine may help you look younger and prevent breakouts.
Not only is it calming, it helps your mind focus, relaxes your muscles if performed correctly, and aids in flexibility.
Yoga moves such as Child's Pose, Down-ward Dog, Legs-Up-The-Wall and Sun Salutations improve circulation and gives the skin a radiant glow.
Exercise is not an elixir of youth, but in addition to diet, lifestyle, supplements and medicines, moderate exercise helps you live with vitality, and perhaps, even extend your lifespan.
Don't work the body too hard, work it smart and watch it age gracefully.
Revathi Murugappan is a certified fitness trainer who tries to battle gravity and continues to dance, but longs for some bulk and flesh in the right places.