Are you still plagued with thunder thighs or a jelly belly that makes you dread bikini season, no matter how hard you work out?
The reason could lie in your DNA. Research has emerged which suggests that genetics could have a far greater effect on our fitness levels than previously thought - basically, we may all be pre-programmed from birth not to respond to certain activities.
Still, all hope is not lost. For while it's impossible to outwit our genes completely, there are cunning ways to overcome their influence so that your workouts succeed.
Running and cycling never get easier:
If you plod away on the treadmill with no discernible progress, it could be that you are genetically programmed not to respond to the effects of aerobic exercise.
A study put nearly 500 sedentary subjects through a 20-week exercise programme which involved pedalling on indoor bikes three times a week.
Professor Jamie Timmons, an exercise scientist at Loughborough University, found that while the majority of volunteers became fitter and markedly increased their maximum oxygen uptake - a measure of aerobic fitness - others saw almost no improvement.
Indeed, in one-fifth of the participants - dubbed the non-responders - their maximum oxygen uptake rose by an almost negligible five per cent. With no differences in the subjects' ages, genders or exercise routines, there was only one explanation for the results: their genes. Hours spent jogging or cycling could be a waste of time for up to one-fifth of the population, Professor Timmons concluded.
What to do: The Professor has developed a DNA test that searches for a total of 40 genes linked to fitness (XRPredict+test, xrgenomics.co.uk) and will determine whether or not you respond to aerobic exercise.
Alternatively, findings suggest HIIT (high-intensity interval training) - performing just four 30-second, flat-out sprints on a cross trainer or exercise bike two or three times a week - helps exercise non-responders reduce blood sugar levels and offset Type 2 diabetes as well as stay trim.
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You can't exercise for more than five minutes
Factors such as muscle fibre ratio and lung capacity are all influenced by genes
Everyone has a physical capacity for exertion, beyond which exercise begins to seem like a struggle.
'Up to 50 per cent of this innate limit is thought to be genetically determined,' says Louise Sutton, a spokesperson for the Carnegie Centre For Sports Performance And Wellbeing at Leeds Metropolitan University.
Factors such as muscle fibre ratio and lung capacity are all influenced by genes, and partly determine how hard you can push yourself before things start to hurt.
When you grind to a halt varies considerably even when basic fitness levels are the same. A study at Iowa State University, in which people were put through the same routines, found that some enjoyed the experience more, the harder the exercise became, whereas others found their mood plummeted as the severity of a workout increased.
What to do: In another study at the Iowa State University, researchers asked overweight volunteers to walk for 20 minutes at a pace they found unpleasant. In one session they were told to spend five of those minutes cooling down with a stroll afterwards.
A week later they were asked which workout they preferred. Twice as many chose the walk with the cool-down. The reason? Their bodies had time to adapt. ‘Get to know your limits,' Sutton says.
You can't shift the fat on your hips
Body shape is strongly influenced by genes
If you are pear-shaped despite your endless fitness efforts, you can officially blame your parents after a study in the journal Nature Genetics suggested the body shape is strongly influenced by genes.
Scientists, led by researchers at Oxford University and the Medical Research Council, looked at the genetic code of more than 77,000 people, and found 13 gene locations that may influence fat deposition on the hips.
Unsurprisingly, they suspected that genes in these regions had a more powerful effect in women than in men.
What to do: You may be born with a certain body type, but there is much you can do to transform your 'pear-shape' into a more hour-glass figure with the right exercise.
Celebrity trainer Matt Roberts suggests ‘interval training where you run for 20 seconds fast and jog for 40 seconds for a total of 10 to 15 minutes' as a great way to remove hip fat.
Then, he says, try adding shape and tone to your upper body with resistance exercises including press-ups, lateral raises and shoulder presses, all of which will help to even out your shape.
It feels too much like hard work
Some people feel pain sooner than others when exercising
Hear a nagging voice in your mind telling you exercise is just too much like hard work? Each of us has that psycho-biological inner voice that controls our behaviour.
But the extent to which we listen to it is and either ignore physical discomfort or succumb to it is partly down to fitness levels and partly determined by our biology.
'To some extent we need that inner voice as a checkpoint to stop us destroying our bodies,' says Dr Murray Griffin, a sports psychologist at the University of Essex. ‘But some people are quicker to react when it tells them that exercise is painful.'
What to do: Working out with other people could help distract you from feelings of discomfort.
A study at Oxford University found that rowers who trained alone withstood less pain than those who exercised in groups.
Or try listening to music while you exercise. Studies at Brunel University showed that your perception of effort drops by as much as 10 per cent when you plug into inspiring sounds. In other words, you feel like you are working less hard.
You can't make your stomach flat
Avoiding processed foods is a good idea for anyone with a stubborn round stomach
Endless crunches and Pilates having no effect on your midriff? Researchers reporting in the Journal Of Nutrition shed light on a possible link between the genes you inherit and the flatness of your stomach. They followed 1,754 French people for seven and a half years, tracking what they ate.
Diet undoubtedly had an effect on a round tummy - eating a lot of saturated fats was a particular risk. But they also discovered that having any one of five genetic traits doubled the likelihood of weight gain in the abdominal area. The more of these traits, the greater the risk for a pot-belly.
What to do: 'Avoiding processed foods is important for those predisposed to a round belly,' says personal trainer Josh Saltzman, who has advised Kate Winslet and Angelina Jolie.
'But they also need to reduce abdominal fat storage through endurance exercise and full-body resistance moves such as squats, lunges and push-ups.'