You probably know loneliness is bad for you. But did you know it can kill you? In fact, it might be just as unhealthy as a pack-a-day cigarette habit.

That's the result of research by Julianne Holt-Lunstad, professor of psychology at Brigham Young University, who conducted a meta-analysis of 148 studies, aiming to find out exactly how bad for you feeling isolated is. Turns out, it's very, very, very bad. "People with stronger social relationships had a 50 percent increased likelihood of survival than those with weaker social relationships," she writes. "These findings indicate that the influence of social relationships on the risk of death are comparable with well-established risk factors for mortality such as smoking and alcohol consumption and exceed the influence of other risk factors such as physical inactivity and obesity."

Think about that for a minute. If you make the effort every day to eat healthy and hit the gym, but you come home to an empty apartment and a limited social life, your odds of dying are higher than if you spent your evenings with a bunch of friends, tossing back beers and snarfing potato chips.

There's a crisis, Holt-Lunstad adds, because loneliness is on the rise, especially in developed, work-obsessed countries like this one. "Over the past two decades there has been a three-fold increase in the number of Americans who say they have no close confidants," she writes. "There is reason to believe that people are becoming more socially isolated."

If anything about this sounds familiar, or if you feel lonely yourself--now is the time to do something about it. Admittedly, if you're feeling isolated to begin with, stretching yourself to go out and create new connections may be the last thing you feel like doing. And yet you must, because your life literally depends on it.

Here are some ideas to get you started:

1. Join a group based on one of your interests.

These days there are interest groups for just about everything. As one example, a quick perusal of Meetup in my area turned up a group of 269 people who live on the East side of Lake Washington and own Schnauzers (all sizes). Look around a little online, in your local paper, and on bulletin boards in your community. You will find a group focused on something you're interested in, I guarantee it.

2. Take a class.

Smart people never stop learning and improving themselves, so pick something you would like to learn to do or learn to do better, from speaking a foreign language to dancing the tango to making sushi. Then sign up and go. You may or may not form lifelong friendships by taking classes, but it will get you out in a social atmosphere. And you'll pick up some new skills as well.

3. Reach out to a long-lost friend.

We all have friends that we love or loved and haven't spoken to in years for reasons of geography, tight schedules, or sheer inattentiveness. Send a text or a Facebook invite, or better yet pick up the phone. There's nothing to cut through loneliness than a talk with someone who knows you or knew you well.

4. Volunteer.

The world is full of community gardens that need weeding, abandoned babies who need to be held, soup kitchens that need servers, events that need organizers, causes that need people to hand out flyers, and on and on and on. You can join a community, make new friends, and make the world a better place all at the same time.

5. Use social media the right way.

Can social media make you feel less lonely? Maybe. In The New York Times, psychologist and author Mitch Prinstein argues that being popular on social media doesn't help fight loneliness because so much social media activity is about accruing status (in the form of thousands of Twitter followers for instance) rather than the likability that helps people remain socially connected and extends their lives. If being on social media is a true form of community for you--a way to share heartfelt thoughts and deep feelings with people you care about and who care about you, though that's a very different matter. Perhaps it can reduce isolation. But it's still important to spend time with people you like in the real world as well.