The new year is the moment when people vow to improve their fitness.
They join gyms, swear off alcohol and adopt detox diets. These resolutions usually do not last beyond January.
But some employers try to help their workers stick to their goals by offering "wellness" programmes.
One of the longest-running examples began in 1979 at Johnson & Johnson (J&J), an American health-care company.
The plan promotes weight loss, smoking cessation and efforts to reduce blood pressure.
The firm claims it reduced medical costs by $400 an employee per year, and resulted in fewer workers suffering from heart disease or high blood pressure.
Yet an examination of the data by Martin Cherniack of the University of Connecticut
found that in 2005-08, a sharp jump in alcohol use, depression and stress among J&J employees occurred.
This coincided with a period when the firm had a target of lifting productivity by 9% a year.
So the employees may have been leaner and fitter, but it is possible that workplace pressure to produce more meant greater stress.
All this suggests that employee well-being is a rather more complex topic than can be tackled by a programme devoted to exercise and healthy living.
A study by RAND Europe, a research institute, found that obvious bad habits
such as smoking and high alcohol use were in fact not associated with lower productivity,
while obese workers were no more likely to take time off than anyone else. The biggest productivity problems were associated with lack of sleep,
financial concerns and mental health issues—factors that may well be directly linked to work-related stress.
It seems reasonable for companies to expect some level of economic return on any wellness programme that they provide.
But the trade-off should not be too blatant. Making employees fitter so you can work them a lot harder
seems rather like drilling your infantry on an assault course before sending them to face the machine guns.
A better impact on morale (and thus productivity) might occur if workers felt that their managers had a genuine interest in their welfare.
Any health programme that tries to alter workers' behaviour at home also raises privacy issues.