In fact, Age UK goes as far as arguing it is just as important as the physical activity bit as loneliness is a risk factor for both cognitive and physical decline.

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Scientists at the Medical Research Council (MRC) at Southampton University allowed for other factors such as poor nutrition and concluded that being underweight or doing little physical activity were responsible for increased risk.

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And physical activity, such as going for a walk or even fidgeting and doodling, can keep people engaged, researchers say.

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Pediatricians could be focusing on recommending less television viewing, for instance, and more physical activity, as well as advising parents to limit children's consumption of juices and sugar-sweetened beverages.

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Training for and participating in vigorous physical activity, such as a marathon, is usually associated with positive health outcomes.

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This means that though many weight-loss interventions suggest walking as the primary form of physical activity, it is probably too hard for many people.

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The researchers found that sitting was associated with a higher death risk after controlling for factors including age, gender, smoking status, physical activity, education, body mass index, as well as living in an urban or city environment.

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