We don't want to worry you, but ...

Cholesterol levels, toxins in food, low-carb vs. low-fat -- as if there weren't already enough health issues to worry about! We hate to be the bearers of bad news, but here are a couple more, particularly prevalent in winter, that may not have crossed your radar yet.

Sitting. A new line of research suggests that just sitting there for long periods endangers your health -- even if you also exercise regularly.

"The person who exercises an hour a day might be better suited to run a 5K, but the person who's been standing and up and around all day may actually be healthier," said Mark Blegen, an associate professor in the Department of Exercise and Sport Science at St. Catherine University.

When you're sedentary, researchers have found, your metabolism plunges, increasing the risk of obesity and diabetes.

What if you have a desk job? One option is to follow Blegen's example: he has used a stand-up desk for two years. Standing for meetings and while talking to students requires "a little bit of a cultural shift," he acknowledged. If you're not ready for that, make a point of taking regular breaks to get up and walk around. While at your desk, maintain good posture, which Blegen said activates more muscles than slouching. And if you watch TV at home, don't just sit there, do something -- stand, exercise, fold laundry.

Shoveling. Minnesotans are practically hardwired to believe in the physical fitness benefits of shoveling snow. Surely venturing out into the cold and doing all that work must be good for us. Otherwise, wouldn't we just use a snowblower?

Indeed, shoveling can provide a great workout, Blegen said. But if you're not in shape, the unfamiliar weight-lifting can leave you with sore muscles. Worse, sudden heavy exertion, combined with the cold's constricting effect on blood vessels, can stress the heart. A 1993 study in the New England Journal of Medicine suggested an increased risk of heart attack while shoveling -- albeit a very small one.

The main problem is that people tend to hold their breath to stabilize themselves while they lift the filled shovel, Blegen said. "That can cause your blood pressure to skyrocket and can potentially be very dangerous," he said.

So go ahead, work those deltoids and burn some calories while clearing the driveway. But warm up gradually and don't overdo it. Most importantly, don't forget to breathe.