The Defining Decade by Meg Jay

The Defining Decade book cover

Why your twenties matter and how to make the most of them now.

High level thoughts

This is a great book for someone in her twenties, who feels uncertain and disillusioned about what life was supposed to look like.

Summary notes

Author’s note, Foreword & Preface

  • Meg Jay is a practicing clinical psychologist in Charlottesville who has had extensive experience with the lives of twenty-somethings.
  • Primary audience: twenty-something who feel lost
  • Secondary audience: thirty-somethings/forty-somethings who also feel the same way.

Preface: The defining decade

  • 80% of the important changes in your life happen by age 35. “The deceptive irony is that our twenty-something years may not feel all that consequential.”
  • The book is about recognizing “the defining twenty-something moments, why your twenties matter, and how to make the most of them now.”


  • Your life (your twenties) are right now. Wake up.
    • Unlike in the past, the new twenties are no longer about keeping a job and raising kids. It’s about something much better – the opportunity to build out the lives we envision for ourselves. We finally have the time to create a life that we choose.
    • However, Meg argues that many of us look at twenties as a transit stop before we find success in our thirties. She recounts her sessions where “too many smart, well-meaning thirty-somethings and fortysomethings grieve a little as they face a lifetime of catching up.”
    • According to Meg, the twenties are the most “pivotal time when the things we do/don’t do have an enormous effect across our life”.
    • Her advice: Treat your twenties, not as a phase, but as the most pivotal growth phase of your life because you won’t have the chance to catch up on your career/family/physical/mental paths once this decade is up. Recognize that this pivotal decade is happening now, in real-time. She will advise further on these 4 topics in the following sections:


  • To form your identity, start working.
    • This chapter tackles the “identity crisis” that so many young people face (I know I did). When we first enter our twenties, we don’t know who we are, and this insecurity about our role in society comes up for the very first time.
    • If you want to have a “clear sense of self, greater reasoning, strong life-satisfaction” you must start by answering this existential worry of “who am I”. The little bits and pieces who make up “who you are” is what Meg calls identity capital. As we enter our twenties we must start doing things that build our identity.
    • The word “capital” is important here because identity capital must also build on itself every year. Each additional piece you add to your identity is a stepping stone for the next one. You must keep growing your identity capital until you are comfortable in your own skin and your identity matures.
    • Her advice: Structure the time in your twenties in a way that is meaningful and intentional. Start building who you are, and keep growing. Look for jobs that will act as building blocks to answering the “who am I” question, and with each completed building block, use it as a stepping stone to get the next building block. Additionally, the more unique your experience is, the more unique your identity is. The important thing is, don’t waste your time on things that aren’t important.
  • Your work/career trajectory will mainly be determined by acquaintances not close friends
    • Meg defines weak ties as those people in your network who don’t make the transition from acquaintance to close friend. Corollary to this, strong ties are those individuals in our network who we like spending most of our time with and who we’d call close friends.
    • Strong ties are fantastic as a support system. Biologically needed for survival, but terrible if you wish to grow/thrive. The reason for this is that strong ties are very similar to who you already are. They live in the same universe as you, and so their inputs are not very helpful if you want to become better/change. Weak ties, on the other hand, live in a different world. They are usually more valuable for change/improvement because “they know things that other people don’t know. Info and opportunity spread farther and faster through weak ties.”
    • Reaching out to weak ties will help you get a very different picture of the same problem. “Suddenly, the world seems smaller and easier to navigate.”
    • Ben Franklin effect:
      • If you aren’t cozy with your weak ties and need to convince them, a technique coined the Ben Franklin effect, can be useful: “He that hath once done you a kindness will be more ready to do you another than he whom you yourself have obliged.” Put simply, if you want weak ties to help you later, start by asking them for specific, actionable help first. Interestingly the opposite is true for strong ties: to get strong ties on your side, do good to them first.
      • Overtures like emails asking for coffee or a quick chat can be dangerously vague for weak ties. Instead “make yourself interesting, make yourself relevant, do your homework so you know precisely what you want or need, and then, respectfully, ask for it.”
    • Her advice: “This is the time to be connecting, not just with the same people having the same conversations about how work is lame or how there are no good men out there, but with those who might see things a little differently. Weak ties are the people who will better your life right now—and again and again in the years to come—if you have the courage to ask them.”
  • Don’t shy away from asking yourself the real questions.
    • Decision paralysis affects most of us twenty-somethings. Sometimes it can feel like we’re in an ocean, and can’t decide which way is the right way.
    • “Unthought unknowns are those things we know about ourselves but forget somehow.” These are dreams we lost sight of, or more importantly, truths we sense but don’t say out loud — things our subconscious is afraid of encountering. Meg uses the ocean analogy to say that we pretend the terrifying decision isn’t picking a direction, it is that once we pick a direction, we don’t know how to go forward. “The more terrifying uncertainty is wanting something but not knowing how to get it.”
    • Her advice: When you have too many choices (30 instead of 3), recognize that too many choices isn’t good for productivity. If something seems like it has no perfect solution, suspect that there might be a “unthought” deeper, subconscious problem that needs a resolution first.
      • “Problems that remain persistently insoluble should always be suspected as questions asked in the wrong way.” – Alan Watts
  • Don’t compare your life to how others talk/share about theirs (facebook/insta)
    • This chapter’s heading pretty much explains itself. Social media like facebook, although useful, has a side effect: constant comparison with other people’s “facebook lives.”
    • “If we only wanted to be happy, it would be easy; but we want to be happier than other people, which is almost always difficult, since we think them happier than they are.” – Charles de Montesquieu, writer/philosopher (quote from the start of the book)
    • Her advice: Stop considering what you “should” do. Do what you really want to do. Make distinction between your goals (things that drive you internally) and your “shoulds” (things that you think you should do, but the truth is you don’t want to, or it just isn’t a priority).
    • My advice: Stop looking at Facebook, and unfollow all your friends so you don’t seem rude. Your time is limited, don’t waste it on the slot machines created by Facebook Inc.


  • 20s are the time to get serious about dating
    • “The most important decision any of us make is who we marry. Yet there are no courses on how to choose a spouse.” – David Brooks (quote at book start)
    • People nowadays are getting married later than before.
    • Her 30-something clients all wish they’d started thinking of marriage sooner.
    • Her advice: If you’re a 20-something, start thinking about serious relationships before it’s too late.
    • This chapter didn’t speak to me much either. I’ve always been a serious person when it comes to the people in my life.
  • Your spouse’s family is important
    • This chapter Meg talks about the importance of your partner’s family. If you can’t get along with them, that is a big red flag.
  • Don’t just move in. Commit first.
    • “It is the couples who live together before being clearly and mutually committed to each other who are more likely to experience poor communication, lower levels of commitment to the relationship, and greater marital instability down the road.”
    • The lock in effect: once you move in together, if you don’t like the other person, your decision to move out won’t be easy because you’ve already gotten too comfy with the side benefits of living together (rent/bills). This is bad cause later this will spill over into your decision to get married, leading to regret down the road.
    • Her advice: Be explicit and make clear commitment to each other before deciding to move in with your partner.
  • Don’t date just about anyone who comes along. Have criteria for yourself and your partner.
    • “…I was concerned that if she kept dating whoever came along, that she might just marry whoever came along at thirty-one or thirty-four.”
  • Your partner’s personality should be like yours as much as possible.
    • You have to have the same personality traits (or as similar) to your partner if you want a long term marriage. Big Five personality test.
    • Aka you have to like the person. Then other stuff comes into play: love/marriage.
    • Also don’t be toxic/neurotic as this is bad for any give/take in relationships.

At this point my eyes were glazing over to the other books in my list like Antifragile by Taleb. Since a lot of these problems/issues are directed at twenty-somethings in US/NA, I couldn’t related to them as much. I’ll end with the end-quote from the book:

“The future isn’t written in the stars. There are no guarantees. So claim your adulthood. Be intentional. Get to work. Pick your family. Do the math. Make your own certainty. Don’t be defined by what you didn’t know or didn’t do. You are deciding your life right now.”

Meg Jay in The Defining Decade