You probably have a plan for your physical health. Maybe a gym membership you use, maybe one you feel guilty about. You might track your steps, your sleep, your protein.
Almost nobody has a plan for their social health. And it might matter more.
That's what social fitness is: treating your relationships like the thing that keeps you healthy, because they are. Here's what it means, why it matters, and how to start building it this week.
What is social fitness?
Social fitness is the ongoing practice of building and maintaining the relationships that keep you healthy and happy. The term was popularized by Robert Waldinger and Marc Schulz, who direct the Harvard Study of Adult Development, in their book The Good Life.
The idea is simple. Relationships aren't something you either have or don't. They're more like a muscle. They get stronger when you use them, and they weaken when you don't. Nobody expects to stay in shape from a workout they did in college. But that's exactly how most of us treat our friendships.
Social fitness vs. social health
Social health is where you are right now: how connected you feel, how many people you could call at 2 a.m., how often you laugh with someone who knows you.
Social fitness is what you do about it. It's the habits, the reps, the weekly plans that move your social health in the right direction. One is the scale. The other is the workout.
Why social fitness matters
The Harvard Study of Adult Development has followed people since 1938, and its biggest finding is about relationships. How satisfied people were with their relationships at 50 predicted their health at 80 better than their cholesterol levels did. And close relationships, more than money or fame, were what kept people happy.
On the other side, the U.S. Surgeon General's 2023 advisory on loneliness compared the health risk of social disconnection to smoking up to 15 cigarettes a day.
So when people call friendship a "nice to have," the research disagrees. It's closer to a vital sign.
Signs your social fitness needs work
Your plans with friends mostly happen on group texts that say "we should hang soon."
You can't remember the last time you saw a friend one-on-one.
Most of your social life runs through your partner, your kids' schedules or work.
You feel busy all the time and lonely anyway.
When something big happens, you're not sure who you'd call first.
If two or more of those sound familiar, you're in good company. You're also in need of a training plan.
How to build social fitness: the 3 Cs
This is the framework I use and teach to companies, schools and parents. It works because it takes the willpower out of friendship.
Close. Invest in people near you. Proximity is the most underrated force in friendship. A friend five minutes away becomes part of your life. A friend 40 minutes away becomes a holiday card.
Consistent. Same day, same time, every week. A standing plan beats a perfect plan. Friendships are built on repetition, and research suggests it takes about 200 hours together to build a close friendship.
Casual. Keep it low-cost and low-effort: a walk, a coffee, a pickup game. The easier the plan, the easier it is for someone to keep saying yes.
A simple social fitness routine
Think of it like a workout plan for your relationships:
Daily: one small touchpoint. A text, a voice memo, a meme that says "thought of you."
Weekly: one standing plan with someone close by. Same day, same time.
Monthly: one reconnection with someone you've drifted from. "Got anything fun coming up?" is the best reopener there is.
Yearly: one ritual you protect, like a trip, a dinner or a tradition that brings your people together.
Social fitness at work
Most adults spend more waking hours with coworkers than with anyone else, which makes work one of the biggest drivers of social health. Teams with real connection collaborate better, stay longer and burn out less. I give keynotes on social fitness and belonging at work for companies, law firms and universities. Learn more about bringing it to your team.
Frequently asked questions
What does social fitness mean?
Social fitness is the practice of building and maintaining strong relationships through regular, intentional habits, the same way you'd maintain physical fitness.
Who came up with the term social fitness?
It was popularized by Robert Waldinger and Marc Schulz of the Harvard Study of Adult Development in their book The Good Life.
What is the difference between social health and social fitness?
Social health describes how connected you are. Social fitness is the set of habits that improve it.
How do I improve my social fitness?
Start with one standing weekly plan with someone who lives nearby, keep it casual, and protect it. Then add small daily touchpoints and a monthly reconnection.
Start your training plan
If you want a weekly push, join 50,000+ readers of The Friendship Habit, a weekly action plan for better friendships that starts with a free 7-day friendship challenge.
For the full story of how I built a new best friendship as an adult, listen to my Audible Original, The Buddy System.
And for the next step, read how to maintain friendships when life gets busy and how to make friends as an adult.
Matt Ritter, The Friendship Guy
