1. Going to bed late
No matter how much you're enjoying that late-night TV drama, it pays to go to bed at a reasonable time.
Losing just 30 minutes of sleep each day during the week can increase risk of diabetes and obesity, says a major new report funded by the Department of Health.
The reason? When your body clock is thrown out of sync, it disrupts your natural hormone levels - and this can lead to serious health problems.
Trouble dropping off? Learn more about sleep strategies
2. Choosing fizzy diet drinks
Think you're keeping your waistline in check by opting for low-calorie drinks? Don't be so sure.
Consuming just one fizzy diet drink a day may add three inches to your waistline over a decade, according to a recent study of 749 pensioners at the University of Texas.
Those who said no to diet drinks saw their waistlines increase by just 0.8in during a 10-year period, compared to an average 3.16in increase among the daily drinkers.
3. Skipping breakfast
So you got up late or you're just not hungry? That's no excuse! An energy-boosting, nutrient-packed breakfast can set you up for the day and reduce risk of both short-term health problems and more serious illnesses.
Need more convincing? Those who skip breakfast at least three times a week are twice as likely to snack on a not-so-healthy, waistline-widening packet of crisps or chocolate bar mid-morning, according to a recent survey commissioned by the Agriculture and Horticulture Development Board.
Diet and wellbeing blogger, Judith Wills lists the best healthy breakfasts
4. Driving short distances
Popping to the shops or visiting a friend? Leave the car at home and go on foot instead. Physical inactivity may be associated with twice as many deaths as obesity, according to a recent study from the University of Cambridge.
Using data on European deaths, the researchers estimated that doing exercise equivalent to a 20-minute brisk walk each day could reduce risk of premature death by 16 to 30 per cent.
Find out how to get even more health benefits from your walks
5. Letting friendships slide
Yes, it can prove trickier to maintain friendships as we grow older - but it's so important to make the effort. Social isolation can increase risk of premature death by around 30 per cent, say researchers from Brigham Young University in the US. Countless other studies have shown that connecting with others boosts both mental and physical health.
6. Not drinking enough water
It's easy to forget to drink water, particularly during the colder months. But if you don't consume the recommended 1.5 to 2 litres each day, you may suffer from mood swings, tiredness and headaches.
In fact, being dehydrated by just two per cent can impair your performance of the simplest of tasks, say researchers at the University of Barcelona.
Find out how much water you really need to drink
7. Not washing your hands properly
You don't need us to tell you to wash your hands after going to the loo, do you? But - whisper it - only 32% of men and 64% of women actually do so, according to a study from the London School of Hygiene and Tropical Medicine.
And if you're in the habit of just giving them a quick rinse, you could still be carrying harmful germs. Use hot water and soap or an alcohol-based handwash for at least 20 seconds: that's approximately the amount of time it takes to sing two verses of 'Happy Birthday'.