How much do you care about your career? The answer is probably: a lot! If you've started your own business, or plan to start one soon, you know how much focus and dedication it takes. If you're trying to make your mark within an existing organization, you know what kind of effort that takes, as well. 

You also know how satisfying it feels when all that hard work pays off. You land a big client, or a round of investment, or you get that promotion you've been aiming for. Having other people recognize you're good at what you do makes you proud of yourself and your accomplishments.

But that can be a trap, says Emily Esfahani Smith, an expert in positive psychology and author of The Power of Meaning. In a Quartz article that's gone viral on social media, Smith recalls the many interviews she conducted with people who experienced huge successes. She's learned from them that if your pride in your own achievements is part of your sense of self-worth, you are likely to be headed for trouble. For one thing, if your company fails, or you lose your job, or something else happens to take away that success, your sense of self-worth is going to go with it. But even if nothing bad happens and you stay successful, over time you may wind up feeling hollow and dissatisfied.

She interviewed an entrepreneur named Anthony Tjan who once led a high-profile startup to the brink of an IPO. It failed, not because of anything he did wrong but because of bad timing. The Nasdaq lost about a third of its value right around the time the company was scheduled to go public. The founders were forced to cancel the IPO at the last minute. Without the expected investment, they were also forced into three rounds of layoffs, and had to file for bankruptcy protection.

Tjan was devastated and humiliated by the IPO's failure, he wrote in a confessional LinkedIn post. But even worse was the realization that he and his partner had focused on the wrong thing--on the glory and riches that an IPO would bring them, not the innovations and service that could make their company useful and meaningful. Since then, the company has been acquired, though not for the big payout Tjan once hoped for. He is now a partner at Cue Ball, an early stage venture capital firm. It's work he finds more satisfying, because its purpose is to help others succeed.

Tjan suffered a very public failure, so it might seem natural he'd turn to a more purpose-driven, less success-focused approach to his career. But the truth is, even when the world gives you every trapping of success you ever dreamed of, you may find that it isn't that satisfying after all.

Successful, but still not happy.

That's what happened to a scientist named John Barnes who participated in a 10-year longitudinal study of 40 men in the 1970s. Barnes had an extraordinarily successful career--he won a Guggenheim fellowship and became chair of his department at an Ivy League college. And yet, in midlife he felt like a failure. He had no goals that seemed worthwhile to him. The praise and public recognition he'd worked so hard to attain now struck him as a symptom of spiritual emptiness. "There must be something missing from one's inner man if you need to be supported by having adulatory comments," he told researchers.

This struggle between working for personal achievement and wealth, or working for a greater good is a natural one for successful people in midlife, Smith writes. And over time, she says, most of us choose to focus on purpose-driven goals rather than worldly ones. That's what happened to Barnes. A few years after his midlife rut, researchers checked in again and found he had resolved his inner conflict. No longer striving toward career highs, he now spent more time being a father to his son. At work, he devoted his time to performing administrative tasks, and to mentoring graduate students. No longer looking for glory, he was instead seeking to be useful, even in a small way.

Depending on where you are in your own career and life, Barnes' story may make a lot of sense to you, or none at all. If you've achieved some of your career goals and found that didn't make you as happy as you thought it would, then looking for purpose or meaning in the work you do, and seeking opportunities to be of service to others, might bring some of the sense of satisfaction you've been missing.

Or maybe you think Barnes' dilemma has nothing to do with you. Maybe you're not ready to give up striving for greater recognition and wealth. Maybe you're happy climbing the ladder and always reaching for the next rung. That's OK too. Making more money can be very satisfying, especially when it means you can afford to provide better for your family or do some good in the community. But if you're like most successful people, the day will come when judging your own worth according to your achievements doesn't work for you anymore. When that happens, Smith has some highly useful advice. Just focus on being of service, on making the world, or maybe just your little corner of it, a better place. Do that, and you'll be leading a meaningful life.