Pursue personal growth that you share — not parallel but joint
Growing alongside a partner or friend, rather than separately, leverages the self-expansion mechanism for both people simultaneously.
Why it works
Individual growth pursued privately does not activate the self-expansion-via-other mechanism. When growth is shared — each person expands, and the expansion is visible and reciprocally incorporated — the relationship itself becomes a vehicle for the most fundamental human motivation the model identifies. The vehicle effect makes the relationship feel alive and central rather than a comfortable backdrop to individual achievement.
How to do it
- Identify a growth area you are pursuing and invite a close person to pursue a related (not necessarily identical) area simultaneously.
- Create a regular brief check-in structure: what have you each learned, tried, or discovered this week?
- Explicitly share what you have learned from the other’s growth, not just what you learned from your own.
Evidence
The self-expansion model predicts mutual expansion as the driver of relationship vitality; research on social support for personal growth projects (Feeney & Collins) shows that growth support — not just responsiveness to distress — is a significant predictor of relationship quality and individual well-being. (observational)
Feeney & Collins is a theoretical and review paper; correlational support is substantial but experimental tests of mutual growth specifically are limited.
Sources
- Feeney & Collins (2015), "A new look at social support: A theoretical perspective on thriving through relationships", Personality and Social Psychology Review
Common mistake
Growing individually and reporting results to the partner rather than structuring the growth as a genuinely shared endeavour — the mechanism requires mutual expansion, not parallel achievement.
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More practices for Self-Expansion Model: How Relationships Grow (and Stagnate) Us
- Do novel, moderately challenging activities together
New and slightly difficult shared experiences restore the self-expansion that keeps closeness alive.
- Practise including the other person in your self-concept
Close relationships develop when you genuinely incorporate the other’s perspectives and resources into how you think — not just spend time with them.
- Audit current relationships for expansion rate
Relationships that stopped expanding tend to feel stagnant — a periodic audit reveals where the growth has stopped.
- Use structured escalating self-disclosure to accelerate closeness
Closeness can be deliberately generated through mutual, gradually deepening disclosure — not just through time.
- Protect expansion by resisting the slide into pure comfort
Long relationships naturally slide toward comfort and predictability — expansion requires deliberate re-injection of novelty.
- Apply the self-expansion framework to individual growth, not only relationships
The same motivation that drives relational closeness also drives individual meaning — seeking growth for its own sake.