Is tearing yourself away from your favourite soap a struggle? Do you break into a sweat at the mere thought of going for a jog? Well, it may be time to learn to love exercise.

The latest research out this week is bad news for couch potatoes. According to a new study of 400,000 people, doing even 15 minutes of gentle exercise a day could reduce the risk of heart disease and increase life expectancy by three years, compared with people who are completely inactive.

Researchers in Taiwan also found that being physically active for an hour and a half each week could reduce the risk of death by 14%.

The British Heart Foundation said the results of the study, published in the Lancet, were encouraging because they showed that doing exercise for even 15 minutes a day was “still better than doing nothing”.

However, it still recommends that people do at least 30 minutes of moderate physical activity at least five days a week if they want to be in the best shape.

The BHF responded to the research by saying that there should be more opportunities for lunchtime activity, affordable sports and recreation, and safe routes to allow people to walk and cycle to work.

In a separate study published in the British Journal of Sports Medicine this week, researchers found that watching an average of six hours of TV a day could reduce life expectancy by a whopping five years.

The study found that extensive TV-watching has a similar impact on life expectancy as smoking and obesity.

Maureen Talbot, senior cardiac nurse at the British Heart Foundation, said: “Sedentary behaviour such as vegging in front of the TV is practically a cultural institution these days and it’s good to relax for a while, but this study supports the view that too much of it can be bad for our health.

“Many of us make a conscious decision not to smoke because we know it’s bad for us, and this study suggests that more of us should make the same kind of pledge about lounging around and watching lots of TV.

“Introducing more activity to our daily lives, whether it’s walking to the shops instead of taking the bus, using the stairs instead of the lift or taking up active hobbies like sport or gardening mean we won’t spend as much time in front of the TV where we’re likely to pile on the pounds.”