The author of To Kill A Mocking Bird, Harper Lee wrote, "you can choose your friends but you sho' can't choose your family."  Of course she is right but she could have added to be sure to choose those friends well, given their long term influence  on our lives.

In fact, a new study shows having friends is the secret to unlocking a lifetime of happiness.
The study is no quick review of previous studies. It is an 80-year-long study from no less than Harvard itself which began tracking 268 students back in 1938.
Participants were routinely surveyed about their lives and mental and physical health.  what the collected results showed was that good friendships protected people from mental and physical decline, and that friendships were the best predictor of a long life.
It turns out that people who were the most satisfied in their relationships at age 50 were the healthiest at age 80 in both body and mind
Smooth sailing wasn't necessarily the marker for a good relationship either.  The study shows that some of the older participants could bicker with each other day in and day out, but as long as they felt that they could really count on the other when the going got tough, those arguments didn't take a toll on their memories or the strength of the friendship.