How much you like something vs how much you can tolerate the cost for it
I was watching The Martian (yes, 5 years late) and thinking about what being an astronaut is like. Sure, I'm not talking about the whole Matt Damon experience of being stuck on Mars alone for 2 years. I'm just talking about generally being an astronaut.
If you ask kids, most kids will probably say an astronaut is one of the things they want to be when they grow up. Why? It's incredibly fun, intriguing, and fascinating; floating in zero gravity and whatnot.
As an adult, you are more disillusioned and generally know that the fun parts of being an astronaut probably account for maybe 5% (or less) of "the job". Most of being an astronaut is about some of the hardest training any humans would do, and studying for the vast amount of knowledge you need to acquire to qualify to be one. You have some rough ideas about everything you'd have to endure, and sustain - whether that's constantly working out to stay in good shape, or being knowledgeable of all the things you need to be knowledgeable of in order to be in space and you know, not be on Earth. Let's just say, it ain't easy.
As an adult, knowing everything you know, most folks would not choose to be an astronaut. That's why there are so few astronauts in our society (compared to other jobs). For those people that remain interested against all odds and do end up becoming astronauts, what I imagine is that in essence, they weigh the fun of being an astronaut to be more than the tolerance they have for the cost of becoming one.
If you generalize this idea, this is true of most things in life. When you choose to do anything (from big to small; like choosing a career, to just daily life things), you typically weigh how much you fun/rewards get out of it, vs what you have to put in. If you decide that you don't want to tolerate what you have to put in, then you stay put, and not do the thing.
Maybe you want to be a software engineer. Some people (like me) think coding is fun, so you put up the effort to go through a 4-year college degree in computer science, endure through the grueling rounds of interviews at companies, and become a software engineer. Maybe you want to play soccer, so you put up with having to expend physical energy the entire time, and practice to get better, so you can play more soccer and have more fun. Or maybe you wanted to watch a movie tonight, but you decide that having to browse through a list and pick a movie you want to watch is too much work, so you end up not watching one.
The sad thing I've realized is that, as one ages, one's tolerance for costs of doing things become lower and lower. Things that you would make a lot of effort to do to give you a bit of excitement when you were young, are no longer things that you would be willing to put up with the cost of doing as you grow older. All of a sudden, one day you realize that the example about watching a movie in that last paragraph, is something that just occurred to you. How is it possible for you to choose to not watch a movie or play a video game just because, you know, starting that activity is already too much work for you?
My next realization is that this is a mindset you have to defeat in order to live a more fulfilling life. As a parent of a 2-year-old, I have to say that my tolerance for doing most things in general have gotten a lot lower over the past 2 years. Parenting is exhausting. Exhaustion does that to you.
We have to keep in mind that it is temporary. Keep the fire of passion burning, because your kid is going to grow up and they will lead their own lives at some point. At that point, you're free of burdens again and you'll have all the time you want in the world again. You'll have less energy, too (because you'd be 50 years old), which is why it's even more important to keep that tolerance of costs of doing things high. If you deplete this tolerance, by the time you retire and your kids are all grown up, all you'll be doing is sitting at home every day. Keep traveling, keep doing cool stuff. Travel, even if you're not backpacking through Europe, even if it's just staying on a cruise ship every month when you're 65. It's still worth it. Keep doing cool stuff even if they are completely useless and you make no money from it, whether it's making useless little gadgets with a Raspberry Pi, or designing completely over-the-top X'mas lights for your house. It's still worth it.
Maybe you won't ever become an astronaut. That's okay. Most of us don't. But at least, keep doing cool stuff. Stay curious, stay passionate. Don't let the daily life of parenting grunt work defeat you. Take your kid(s) to travel even if it's a lot of work; even if they whine the entire time. Sure, the traveling might be for them. It's for building their childhood memories. But remember, it's for yourself too. It's for yourself to keep your fire burning and not let it burn out. One day you'll be an empty nester. When that day comes, you want to be the 50-year-old who climbed up Huayna Picchu. Not the one sitting at home every day. (I mean, that'll probably happen on most days still. You can't travel every single day. But do try to go to Huayna Picchu.)