Usually the little inner voice starts piping up as you lie on the couch. "Go ahead, have another piece of candy," or, "Take a handful of those potato chips."
The voice is that of one's weaker self, which has to be nourished and acknowledged, said professor Ingo Froboese of Germany's college athletic health center in Cologne.
"You have to let that inner voice win sometimes, but you also have to show it clearly who's the boss of the household," Froboese said.
"Especially in winter, everyone should set concrete exercise goals and schedule activities," advises health psychologist Sonia Lippke of Berlin's Free University. Lippke and fellow psychologist Jutta Wittig are working on a study of the weaker self and how people can be active in a healthy way despite it.
"A lot depends on setting realistic goals," Lippke said.
People who already know that they do not really enjoy working out should not suddenly become addicted to it, said health expert Stefan Buchner of Berlin. It's more worthwhile for a person to think back on an activity that gave them the most enjoyment and pursue that.
"Whatever they do, people should not go headlong into some trendy sport and buy all the equipment for it at the first opportunity," Buchner said.
Reward is a good means to coax the weaker self into agreeing to leave the couch. The reward could be time in the sauna, a massage or a nutritious vitamin-rich drink, any of which can be enjoyed at the gym immediately after a workout, Buchner said.
"When it comes to nutrition, complete bans on certain foods usually don't work," Lippke said. It's also an innate human instinct to fatten up just a little before and during winter even though it's no longer necessary because of the way homes are heated in the 21st century in the Western world.
There's no sin in nourishing oneself with all types of foods, Froboese said. The trick is to reach a stable weight and stay there.
A diet heavy in fat and little activity is the worst combination.
The extra calories in the fat, however, can be offset by daily activities like climbing stairs or getting off the bus one station early, the sports professor said. He advises people to have something up their sleeve to increase their level of activity as alternatives to jogging or cycling.
"In the midst of winter people find thousands of excuses not to exercise, such as it's too dark or wet out," Froboese said. People should consider signing up for a course in a nearby gym or arranging appointments with a home fitness trainer.
Buchner also knows how difficult it is for some people to get out and exercise. Once they are home, the gym suddenly is kilometers away, even thought it's just around the corner.
To overcome this problem, Lippke recommends people ask a neighbor about going together.