People can do some easy movements like stretching their arms and legs, moving their neck and shoulders when they are watching TV.
"Just don't sit on the sofa without moving at all," says Lu.
Alternatively, they can play badminton or ping pong, which are popular all year round and not influenced by the weather.
"Whether it's cold or rainy, I can enjoy playing badminton with my friends," says Chen Yinfei, a 35-year-old receptionist in an investment consultancy.
After she graduated from college, Chen's work schedule didn't permit the same kind of regular exercise to stay healthy.
"Since we started work, we seldom have the chance to play sports. We don't burn many calories, especially in winter," she says.
In order to keep fit, Chen has been playing badminton every weekend for two to three hours.
That's good, but according to the national exercise survey, burst of intense exercise once a week is not enough.
Regularity is the key.
Sweating white collar
Jiang Qi always gets up early and jogs in the park for an hour every day before he goes to work.
"Maybe it's cold, but it's the best time to take off your thick coat, change to warm sportswear, go for a jog and breathe fresh air," says Jiang, 38, who works in an advertising company.
He says it's the best way to start the day, not only for health and stamina but for overall well-being and a good state of mind throughout the day.
He's been doing it for four years.
From expert
Jogging (not running) is probably the best aerobic exercise. The oxygen that the jogger breathes in is sufficient as the movement intensity is low.
Jogging improves blood circulation and cardio-vascular health, lowers cholesterol, improves metabolism, burns calories and contributes to general fitness. It also can elevate mood.
"For middle-aged people, jogging is a very good way to prevent arteriosclerosis and diseases of aging," says Lu.
To get the maximum benefits, jog for at least 30 minutes three or four times a week.
"The speed should be controlled to slow or middle-speed, according to everyone's age and heart rate," adds Lu. Beginners can start at 10 minutes and gradually jog for longer periods.