5 good habits that hurt you

By Martha Schindler

When it comes to our health, some of our most cherished assumptions about eating, working out, body fat and relationships are wrong. In fact, some of our "healthy" convictions can be downright dangerous. Here are five of the most commonly made mistakes.

1. "I rarely miss a day at the gym."
Everyone needs a break from their workout routine -- even Olympic athletes -- for two reasons. First, your body needs new challenges in order to maintain or improve fitness. Second, overtraining can lead to muscle aches and tears, joint injuries, lack of energy, unrelenting fatigue, decreased immunity, even depression, says Jack Raglin, Ph.D., associate professor of kinesiology at Indiana University, Bloomington, who studies the psychological and physical effects of exercise overload. "If you never miss a day at the gym, that means there's nothing in your life that's more important," he says.

Instead: If you're gearing up for an event like a 10k, you might push yourself harder than usual. At other times, give yourself a break from the gym. Walk outside. Schedule days off and enjoy some social time with friends. Flexibility is key.

The truth is that going as long as a week without breaking a sweat won't impact your fitness significantly -- but going too long without a break from your workouts definitely will. "It's a case of diminishing returns," Raglin says. "Doing more and more -- without building rest and recovery into your routine -- does you less and less good."