When creating a retirement planning checklist, one way to organize your thoughts about the big questions is how will you stay in touch with your network of family, friends, and former colleagues — as well as meet new people. You don't want to age lonely.

Scholarly research and everyday experience both come to the same conclusion: Loneliness is a threat to the quality of life of elders. "Loneliness kills and disables more people than smoking," Dr. Paul Tang, chief health transformation officer at the Silicon Valley based IBM Watson Health, told me in an interview last year. "Social connectedness is one of the best contributors to meaningful longevity."

The "loneliness lens" is a savvy way of thinking through basic retirement age questions. Among them: What will you do to stay engaged after saying goodbye to colleagues? Where will you live? How will you get around?

Take engagement. Finding paid work during the traditional retirement years is an option more people are embracing, usually part-time work, jobs with flexible schedules and self-employment. A job brings in money, of course. But the workplace is also a community. People care if you don't show up.

As economists Axel Borsch-Supan and Morten Schuth put it in "Early Retirement, Mental Health and Social Networks": "Even disliked colleagues and a bad boss, we argue, are better than social isolation because they provide cognitive challenges that keep the mind active and healthy."

Volunteer activities, lending a helping hand at church or temple and taking care of grandkids are also activities that involve community. The same goes for heading back to class. Thanks to Minnesota's Senior Citizen Education Program (SCEP), if you are a Minnesota resident and 62 years and older you can audit courses free at the Minnesota State Colleges and Universities and the University of Minnesota. Want credit? The charge is a $10 per credit.

What about getting around to stay in touch with your network? What will you do if you can't drive anymore? Is public transportation a practical option? A cab? Or should you move to a neighborhood that doesn't rely on cars?

Speaking of neighborhood, where are you going to live? The typical answer is to age in place — the home. The idea is understandable, but is it practical with the passage of time? You don't want to end up spending more and more time by yourself in your home without easy access to your network, especially late in the elder years.

Christopher Farrell is senior economics contributor, "Marketplace," commentator, Minnesota Public Radio.