For many of us, our 20s feel like a liquid decade -- everything is in flux as we work out what we want to do professionally and who we want to be (and be with) personally. It's in your 30s that life seems to settle down into something firmer and more solid.

But what if the form it takes isn't as you hoped? How do people end up moving into the middle of their lives lugging mistakes and regrets to either be born or undone? Or to put it a simpler way, what are the most common ways people mess up their 30s? That's the subject of a fascinating and revealing recent thread on question-and-answer site Quora in response to a poster who asked, "What is the biggest mistake you made in your 30s and what did you learn from it?"

Many of the mistakes shared on the site are highly unusual. It's unlikely you'll accidentally hand $80,000 to the Ukrainian mafia or spend an entire year playing poker like a couple of those who answered, but a few general themes emerged.

1. Neglecting people in favor of work.

Regret over working too hard is one of the top end-of-life regrets. Apparently, it's a behavior (and a regret) that takes hold early. The most common response on Quora was some version of a wish that the poster could have struck a better work-life balance in his or her 30s.

"I took getting pregnant for granted," entrepreneur coach Alison Whitmore confesses, while David K. Storra says he "took an amazing woman for granted." Indeed, many, many answers revolve around the common theme of obsessing about work at the expense of close personal relationships.

The bottom line is perhaps best summed up by product designer Michael Dorian Back: "Don't just work. Make memories. The older you get, the harder it is to make meaningful relationships. Foster those up while you're young."

2. Not finding the right balance between passion and money.

This is a funny one as responders confessing to errors split pretty evenly between two ways to go wrong. A good many warned against getting too comfortable with a certain material standard of living and letting your dreams -- or your ideals -- slide. The most popular answer of all, for instance, is an anonymous responder who says his biggest mistake was that he "got addicted to a monthly salary." Several others say their biggest mistake was persevering in careers they knew were wrong for them out of comfort. Another anonymous responder regrets "too much work, to have too much money, just to waste too much in luxuries... luxuries I thought I deserved because I was working too much!"

Meanwhile, roughly an equal number regretted pursuing their passions at the expense of sensible financial planning. One anonymous poster confesses he "took for granted the 'monthly salary' life, ventured out on the wild terrain of entrepreneurship/startups/turnarounds without a basic assessment of risks." Another poster named Tom Lambert says something similar: "I wish I had thought about money just a little bit ... [money] can be an incredibly useful tool for doing good in the world or just enjoying yourself. Having a cushion really decreases the amount of stress that revolves around money, both short term and long term."

The takeaway, perhaps, is that balance in this area is both really important and really tricky.

3. Thinking you have to follow some sort of script.

Writer Himay Zepeda encapsulates this one well. His top mistake was "obsessing too much about my life plan. I think I put an excessive amount of pressure on myself. It didn't let me enjoy what I was doing. Instead of focusing on what is, I was obsessing over what could or should be. It took the piss out my life, and made me ignore my blessings."

In a similar vein, yoga teacher Claudia Azula Altucher calls herself out for falling victim to "bulls**t stories society will convince you to believe," the necessity of home ownership among them. "I BELIEVED: buying-home = happily-ever-after. And that was just one, among many other stories like that... I was a sucker for lies," she writes. A chief technical officer, Scott Faisal, too, "bought a home because everyone else was buying one."

The common fallacy is a belief there is some plan or script, often set by others but sometimes by you, that you can make your life conform to through a supreme act of will. Sure, having goals is important, but anyone who reads these answers would also have to conclude it's a mistake to adhere to them too rigidly. Skip the detailed life plan in favor of listening to yourself, keeping an eye out for opportunity, ignoring unhelpful advice or generic expectations, and of course correcting as necessary.

Are you brave enough to share the biggest mistake you made in your 30s so others can learn from your experience?