Self-Development: Why Does Investing in Yourself is the Least Wasteful?

An employee has been waiting two years for his manager to become fairer.

A mother is waiting for her son to “grow up” and finally understand.

A young man puts off every step until “things get better.”

They’re all waiting for something outside themselves to change. And it might. Or it might not.

The point isn’t that the world never changes, or that people can’t be influenced. It’s that the most changeable thing in your life is you.

Trying to change someone? Maybe they’ll change, maybe they won’t.

Waiting for a situation to improve? Maybe it will, maybe it’ll drag on.

But what goes with you everywhere is the way you think, the way you react, and the choices you make.

That’s why I believe developing yourself is the least wasteful investment you can make in your life.

Why You, Specifically?

The idea is older than we think.

About nineteen centuries ago, the Stoic philosopher Epictetus taught a simple distinction that became one of his best-known ideas: some things are up to us, and some things are not.

What’s up to us, as he explains it: our judgments, our attitudes, our intentions, and our actions.

What’s not up to us: our bodies and what happens to them, our possessions, our reputation, whether our projects succeed or fail, and other people’s choices.

Notice that “other people’s choices” is on the second list.

That doesn’t mean people don’t matter to us. It means their decision is, in the end, theirs.

When you pour all your energy into changing someone, you’re investing in an account you don’t hold the key to.

When you put it into how you deal with them, you’re investing in the one thing you own almost entirely.

But Do People Really Change?

Plenty of people say, “This is just who I am. I’m not going to change.”

Research says something different, if quieter than what motivational books promise:

• A broad review: In 2017, a University of Illinois team led by Brent Roberts pooled the results of 207 studies covering more than twenty thousand people. They found that interventions, mostly psychotherapy lasting about twenty-four weeks on average, were linked to noticeable change in personality traits, most clearly in emotional stability. And in the studies that followed participants after the intervention ended, the change seemed to last. But the researchers themselves cautioned that this isn’t a complete personality overhaul, and that most of the measures relied on participants’ answers about themselves.
• Intentional change: In two studies of university students (2015), researchers Nathan Hudson and Chris Fraley asked participants to name a trait they wanted to change, then followed them for sixteen weeks. Those who wanted to change did change in the direction they wanted, more than the others, though the change was modest. The surprise: vague, general plans backfired, while specific plans of the “if this happens, I’ll do that” kind helped.
• The End of History Illusion: In studies of more than nineteen thousand people aged 18 to 68, people acknowledged they had changed a lot over the past decade, yet expected to change only a little over the next one. As if each of us sees ourselves as the “final version.” Still, some researchers have criticized this finding because it compared different people rather than following the same people over time.

The honest takeaway: people do change, slowly, and within limits.

And since you’re going to change anyway, the real question is: will you leave that change to chance, or steer it?

What Kind of Change Do I Mean?

Changing yourself isn’t an admission that you were wrong. Sometimes it’s proof that you’ve become more aware.

And I don’t mean change for show, or a fake, perfect version of yourself that you post on social media.

I mean quiet change:

• Clearer thinking: Knowing what you want from a meeting before you walk in, not after you walk out.
• Calmer reactions: Reading a provocative message in the family group chat, and holding your reply until morning.
• Better boundaries: Telling a friend who’s asking to borrow money for the fourth time, “I can’t this time,” without spending an hour justifying and apologizing.
• Fewer choices, but sharper ones: A freelance designer deciding to work with three clients she understands instead of ten who drain her.

None of this shows up in a photo.

But all of it shows up in your life.

The Paradox: When You Change

When you change, the way you interact with the world changes.

Not because the world suddenly changed, but because you’ve started dealing with it differently.

A father used to raise his voice whenever his son fell behind in his studies. He decided to sit with him for ten minutes every evening and ask about his day instead of his grades.

The son didn’t become a top student in a week. But the house grew calmer, and the son started telling his father what was worrying him before it turned into a problem.

And an employee who used to meet her manager’s feedback with instant defensiveness started saying, “Let me look it over and get back to you.” The tone of every meeting changed.

People respond to what we offer them. And when what you offer changes, what comes back to you usually changes too.

Usually, not always.

When Does “Start with Yourself” Become Unfair Advice?

Here we need to be fair.

“Start with yourself” doesn’t mean everything that happens to you is your responsibility:

• When the injustice is real: Someone who lost their job because the company shut down an entire branch doesn’t need “self-development” to understand what happened. They need to know it wasn’t in their hands, and then work on what is.
• When development turns into an endless race: If every book, every course, and every morning routine becomes proof that you’re “still not enough,” that isn’t development. It’s self-flagellation in nice clothes.
• When it becomes a substitute for standing up for your rights: Improving the way you talk to your manager is a good thing. But sometimes, developing yourself means demanding what you’re owed, or leaving.
• When you’re sold a quick promise: Any course that promises your life will “change in a few days” deserves a critical question before it deserves your money.

And even at its best, investing in yourself doesn’t guarantee results.

It’s simply the least wasteful investment, the most lasting, and the one with the longest return.

A Four-Week Exercise

Try it calmly, without pressure:

1. Split a page in two: “Up to me” and “Not up to me.” Write down one problem that’s on your mind and sort its parts into the two columns. Example: your manager’s decision isn’t up to you; the way you present your work is.
2. Pick just one behavior: Don’t try to become a new person. Example: “Hearing criticism all the way through without interrupting.”
3. Turn it into an “if… then…” plan: Example: “If someone criticizes me in front of others, I’ll take a breath and say, ‘That’s a fair point, let me think about it.’”
4. Review it every week: Don’t just ask, “Have I changed?” Ask, “Has the way people around me treat me changed?” Example: Have your discussions with your colleague become shorter and calmer?
   

A Simpler Mental Model

Imagine you have three accounts to invest your energy in:

• People: They might change, or they might not.
• Circumstances: They might improve, or they might drag on.
• You: The only account you hold the key to, and the one that goes with you wherever you go.

Don’t close the first two accounts.

But put the biggest share into the third.

No one can guarantee you the outcome.

But everything you build inside yourself stays with you, even when everything around you changes.

Start with something small: pick one reaction you wish were calmer, and just watch it tomorrow.

The world might not change.

But the way you stand in it will, and that alone is a lot.

Further Reading

• Epictetus — Stanford Encyclopedia of Philosophy (Margaret Graver), 2008, rev. 2025: A reliable explanation of Epictetus’s philosophy and the distinction between what is up to us and what is not.
• A systematic review of personality trait change through intervention — Roberts et al., Psychological Bulletin, 2017: A summary of the review that pooled 207 studies on personality trait change through intervention.
• Counseling, antidepressants change personality (for the better), team reports — University of Illinois News Bureau, 2017: A plain-language explanation of the same review, with the researchers’ caveats about how big the change is.
• You can change your personality at will — The Psychologist (BPS Research Digest), 2015: An overview of Hudson and Fraley’s study on intentional change, and why specific plans work better than vague ones.
• End-of-history illusion — Wikipedia, 2026: A definition of the end-of-history illusion, the 2013 study, and the criticisms leveled at it.