Maintaining personal relationships requires more effort in your 30s than it did in your 20s.
Your 30s are typically a time for settling down after using your 20s to take risks and find yourself.
Many 30-somethings are busy raising a family and rising through the hierarchy at work.
Those who have already been through that decade say that as their responsibilities accumulated, it became easier to neglect relationships and ignore opportunities that they would never get again.
Quora users discussed lessons they learned in the thread: "What is the biggest mistake you made in your 30s and what did you learn from it?"
We've collected some of the best responses:
They abandon their loftier aspirations.
Twenty-somethings are often willing to settle for a job they are not passionate about, but before they know it, that job turns into their career. An anonymous poster writes that his or her biggest mistake of his or her 30s was to become "addicted to a monthly salary," in the sense that he or she settled for job security over career satisfaction.
If you've ever wanted to start a business or pursue a side project, it will only get more difficult as your responsibilities increase.
They put their career ahead of family and friends.
"Don't just work. Make memories. The older you get, the harder it is to make meaningful relationships. Foster those while you're young," writes Microsoft product designer Michael Dorian Bach, who is now in his late 30s.
They neglect their health.
Bach writes that the pursuit of a career can also be a drain on one's health. "Be healthy. That is priority 1. Don't get into your 30s being slow and tired all the time. It sucks," he says. Develop an exercise routine, and enjoy your mobility while you're still young.
They miss the chance to have kids.
CEO coach Alison Whitmire shares a personal story about how she took getting pregnant for granted in her 30s and chose to pursue a new career opportunity instead of trying to have a child. Years later, after a failed pregnancy and then a failed marriage, she remarried and had a baby at 43. She realizes now that no one is ever adequately prepared to have a child, and if you want one, it's best to do so before it's too late.
They don't spend enough time with their aging parents.
Entrepreneur and blogger James Altucher, who is now 46, writes about a particularly difficult memory for him: "When I was 34 I hung up the phone on my dad in an argument and never returned his calls. Six months later he had a stroke and died. A week before that he had emailed me to say hello but I didn't return the email. I'm sorry, Dad."
It can be easy to forget that your parents grow older as you do. Don't take them for granted.
They don't set up a financial foundation for the future.
Altucher writes about the many times in his 30s he bet practically all of his money on a business venture and then lost all of it. Altucher is doing well now, but he looks back on his failures as the result of recklessness.
As your responsibilities grow, it can seem like what you put into savings won't amount to much come retirement, but it will only become harder to start saving in your 40s.
They stop having fun.
Just because you're not in your 20s anymore doesn't mean you need to give up enjoying life. Bach says he spent the early half of his adult life chasing money, and it only made him unhappy and more cynical about life.
Go on dates with your significant other. Take your kids on trips. Go to concerts with your best friends. Just don't forget that the money you work to make is useless if you're miserable.
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