I have a friend who was in his late 30's when he had his first kid. Now, he is 50 years old, his youngest kid is 8 years old, and I have heard him remark on several occasions that when he is attending his second child's high school graduation, he will be a 60-year-old man.

I've heard him remark somewhat wistfully that he wishes he had been able to spend his 30's (when he was younger and had more energy) running around in the park and tossing around a frisbee or rollerblading with them, rather than struggling to keep up with them now as a 50-year-old. And mind you, he's a pretty healthy guy (was a college athlete, not currently overweight or with any chronic health problems), he can bench press more than most guys half his age, and he still wishes he'd had those younger years to spend with his kids. I've also heard him mention once (in a much more somber tone) that if his sons wait as long as he did to have kids, he might not get to see his grandkids grow up, and even if he does get to watch them grow up, he will be a very old man by the time they're old enough to swim or throw a frisbee. (If physically keeping up with your kids as a 50-year-old is tough, imagine trying to do the same thing as a 80-year-old grandparent.)

Here's a question: would you rather spend your 30's globetrotting (or otherwise "living life on your own terms"), and then be raising kids into your 50's? Or would you rather spend your 30's raising kids, and then have your 50's to go on globetrotting adventures? Everything I've heard from parents tells me that raising kids takes immensely more energy than touring Europe.

Another thing that might go overlooked is that although I've seen some parents abandon hobbies to spend more time with their kids, I've seen some people with hobbies that they've gotten to share with kids that have been a great bonding experience, be it something like woodworking or playing a musical instrument or a martial art or running a side business on Etsy. And even if it's something that doesn't involve the kid, parents still get to have lives; I have a friend who has a full time job, is raising three kids, and still managed to write a novel in the past year. Modern American society has burdened parents (and kids) with lots of obligations like soccer practice/youth sports league of your choice, a constant regiment of scheduled afterschool activities and an attitude that says if you let your kids play in the park unsupervised you're a neglectful parent, but most of the anecdata I've observed tells me that both parents and kids seem to enjoy themselves more and have better relationships when they have large amounts of unscheduled time during the week; one of the things I'm most grateful to my parents for is the large amounts of time that they left me to entertain myself and discover my own hobbies.

Here's another thing: after your kids grow up, you (hopefully) get to be friends with them. My parents (now mid-late 50's) are empty nesters, and one thing that I'm constantly struck by is how much I enjoy being friends with them, traveling back to their part of the country once a year to go on vacations together once a year, calling them every week to commiserate about the trials of adult life, and so on. We have the kind of incredibly tight familial bond that you only get from living under the same roof with someone for 18 years and they're also incredibly good friends. If all goes well, I'll be able to spend the next several decades with my parents continuing to be a part of my life, and that's something that I'm immensely grateful for. The earlier you have kids, the more years of your life that you get to spend with them, and the more years of their life they get to spend with you.