The days are getting shorter, the nights colder. The timing feels just about right to wrap yourself in your coziest couch blanket and get your Netflix binge on for months on end.

While hibernating all winter sounds appealing, it might not be best for your mental health. Staying physically active can help prevent depression, new research finds. The results of three studies suggest there is a link between low physical activity and depression. This is true for both men and women.

Specifically, the researchers found low cardiorespiratory fitness was associated with a 75% increased risk of depression. Medium cardiorespiratory fitness levels were associated with an increased risk of about 23%.

More than a million people participated in the studies, and this is what the researchers concluded in their analysis: Cardio is extremely effective at preventing depression. They even went so far as to say being inactive is a risk factor for depression. The study did not explore cardio as treatment for depression. It was only examined as a preventative measure.

Other reasons cardio happifies your brain

Throwing on your running shoes or hitting the cardio machines at the gym has plenty of other benefits. Studies have found that cardio workouts can deliver creative boosts to the brain and help you be more productive. Researchers have also found that just 20 minutes of moderate activity in the morning can improve your mood for up to 12 hours.

What about other types of exercise, like yoga and strength training? The benefits are many. A recent study found lifting weights keeps your brain young while another revealed that 20 minutes of yoga can boost brain function.

It seems a varied exercise routine is probably the best way to cover all your bases. But if you don't have hours of free time a day to dedicate to all these forms of exercise, I wouldn't worry too much about it. As the oldie-but-goodie Freakonomics podcast episode "What's the "Best" Exercise?" revealed, the best exercise for you is whichever kind of exercise you like to do. Because that's what will keep you doing it. Chances are, your brain -- and your body -- will benefit one way or the other.