Are you in your 20s? Are you an entrepreneur? Have you been told by your friends, your advisors, and your professional peers that now is your time to build your own life and not worry about things like settling down and having children — especially if you’re a female entrepreneur?

It makes sense, right? This is the only time in your life when you have no ties, no mortgage, and no kids to support. This is the only time you can really do something ambitious. And let’s face it, you’re not ready, anyway. You’re busy building your company, figuring out who you are, what you want. You get laid on a regular basis; it’s not like you don’t have a “love” life.

And everyone around you agrees. Everyone! Now is the time to live! You’ve moved to New York. Or San Francisco. Or Palo Alto. Or Boston. With the express purpose of building something. This is a noble cause. There is nothing more professionally satisfying as building something. Something you love. Something you can “get behind.” But…there was this girl. This guy.

Eh, fuck it. You’re busy. You have more important things to do. Changing the world is a full-time job and if you don’t do it now, when will you?

Here’s the thing: I know you. You’re probably one of the many people I’ve mentored or hired. On multiple occasions, you’ve explained to me (as if I were your batty old aunt, but I’m not taking it personally) that you have no time to get to know anyone because you’re busy doing your work. This is a complete fallacy. Work and relationships are not incompatible. (Ask Mark Zuckerberg.)

I’ll wager that there is something about big transient cities that distorts everyone’s sense of time. You become convinced that you have time for everything you find challenging, that your ultimate horizon is infinite. This is only the beginning for you. But you don’t know how much time you have.

And even if things go well for you, your time is finite. You can’t figure out your professional life now and your personal life later (unless you’re the rare 13-year-old entrepreneur, in which case, I might demur).

And here is why: As with coding and management and matters of finance and marketing, relationships have a learning curve. You need to learn the basics of “relationshiptiva” (yes, I made up that word): how to deal with sexual etiquette, with the mundane, with scheduling, and some equitable plan for who’s supposed to pay for dinner or wash the dishes this time. These are basics. And if you’re learning them in your 30s, it’s going to be much harder.

Because in a few years, however young you think you are (how old is 30, really?), you will be approaching midlife and you won’t be as adaptable as you once were. There are reasons for this, many of which are biological. Your body won’t respond the same way. You’ll have knee problems that didn’t exist when you were running sophomore track. You can’t stay out till 4am anymore, because now the same alcohol intake has somehow resulted in a hangover that’s a multiple of what it once was — and you will never ever have appreciated a nice, soft pillow more. And if you think you can fend these things off with diet and exercise, you should probably buy a good solid book on the aging process or find a professional athlete over the age of 30 to talk to. They will speak of massage therapists and bone density and necessary nutritional supplements. You can mitigate these things, but you can’t entirely avoid them.

But that is not the point. The point is that 30 (or 32 or 35) is not the age when you want to start trying serious relationships for the first time.

Because learning how to develop a meaningful, sustainable relationship and keep it healthy takes some extended practice. You have to get beyond the basics — the sexual negotiations and the decisions about whose clothes go where and how to talk about exes. You have to figure out how to fight well, how to negotiate major value conflicts (if you can — some are impossible), and how to deal with the inevitabilities that come your way.

And those inevitabilities are myriad: At some point, you and your partner will go through a period of disillusionment when someone else turns your head or your partner’s. Maybe you have an affair, maybe you don’t. At some point, one of you will have significantly more career success than the other. This will become a point of tension. As will the disparity in income that usually accompanies it. At some point, you will disagree on how to raise your child and you will each wield the child as the ultimate weapon in a battle of wills. (I’m just doing what’s best for our child!) And at some point, one of you will have a major life issue that costs you everything or close (cancer, financial ruin, miscellaneous crisis), and the other person will have to decide to commit to or not.

It’s not a question of whether each of these things will happen; it’s a question of when. And if you do decide to spend a life with someone, you have to decide that you are willing to face all of these things and acknowledge that some of them could happen sooner than you expect.

Relationships are too important to learn how to face those issues at the last minute. You have to go through a few of them to know how to properly conduct one. You have to fail. You have to date a few terrible people. You have to be the asshole yourself sometimes. You have to learn how not to be the asshole. You have to spend tons of time together — so much time that sometimes you feel indistinguishable from each other and you find that both reassuring and disturbing. You have to have a vicious fight and know it’s not ending you and that you’re going to have to work to repair it and that the effort is worthwhile. These things take time.

I’m not suggesting, mind you, that you settle down in your 20s. I don’t envision you in a ranch home in the suburbs at 26, feeding your toddlers Cheerios and pureed organic carrots, and carting them to and from soccer practice in the family. I’m just saying that it’s worth it to look at your romantic relationships nakedly. Work at a relationship the way you work at your work. Spend the time. Make the effort.

You need the practice. You need to learn. Some of you can wait another 10 or 20 years to do that. And some of you may be the rare bachelors and bachelorettes who have no intention of ever being in a serious, committed relationship ever. But not most of you, especially if you’re envisioning a spouse and kids sometime before you can start collecting social security. You need time — and lots of it.

And you need to remember that work is not everything. I met my fiancé at work, which is not a way that Detached Professional Me would ever advise anyone to go about meeting people. Under the circumstances, we had to decide fairly quickly whether we were willing to get fired. What was more important: the job or the relationship? We picked the latter. Fortunately, nobody got fired. But if I had been sent packing, I wouldn’t regret it. Jobs are replaceable. People you truly love are not.

I think it’s fair to say — with no scientific evidence — that deathbed wishes rarely include, “If only I had put another 20 hours a week in at the office!” But that guy, that girl? You might regret that.

Elizabeth Spiers/Quartz