This retirement planning gap is 'hidden in plain sight,' Harvard professor says

cnbc.com:

For many people, retirement planning is all about money: how to invest, how much to save, when to claim Social Security, how to best withdraw from accounts.

Finances in retirement are an acute fear. About 2 in 3 people worry more about running out of money than about death, according to a recent poll by Allianz Life.

Yet, there's a notable lack of attention and concern given to the social aspect of retirement, experts said.

It's a facet of retirement planning that's almost «hidden in plain sight,» said Robert Waldinger, a clinical professor of psychiatry at Harvard Medical School.

Waldinger is the fourth director of the Harvard Study of Adult Development, which began in 1938. The study, the longest-running of its kind, has tracked thousands of Americans throughout their lives and across different generations for the past 86 years.

A core, and perhaps surprising, finding: Having good relationships — whether with partners, friends, family or others — is the «strongest predictor» of living a long, healthy and happy life into old age, more so than health factors such as high blood pressure and cholesterol, Waldinger said.

Money is the «obvious» focus when it comes to retirement planning, Waldinger said.

"[But] if you want to be happy, it's mostly not about the money," he added.

Put another way: «Social connections are really good for us» and «loneliness kills,» Waldinger said in a 2015 TED Talk titled «What makes a good life?» It's one of the most-viewed TED Talks.

Relationships play a big role in preventing and relieving stress.

When someone is stressed, their body revs up into a fight-or-flight mode, triggering reactions such as an increased heart rate, Waldinger said.

Having someone to talk to or even complain to at the