The Atlantic:

To begin with, don’t dismiss the humble acquaintance. Even interacting with people with whom one has weak social ties has a meaningful influence on well-being. Beyond that, building deeper friendships may be largely a matter of putting in time. A recent study out of the University of Kansas found that it takes about 50 hours of socializing to go from acquaintance to casual friend, an additional 40 hours to become a “real” friend, and a total of 200 hours to become a close friend.

If that sounds like too much effort, reviving dormant social ties can be especially rewarding. Reconnected friends can quickly recapture much of the trust they previously built, while offering each other a dash of novelty drawn from whatever they’ve been up to in the meantime. And if all else fails, you could start randomly confiding in people you don’t know that well in hopes of letting the tail wag the relational dog. Self-disclosure makes us more likable, and as a bonus, we are more inclined to like those to whom we have bared our soul.

The academic literature is clear: Longing for closeness and connection is pervasive. Which suggests that most of us are stumbling through the world pining for companionship that could be easily provided by the lonesome stumblers all around us.