44 year old with three boys ages 12, 10 and 4. Those early years were absolutely the most difficult and lonely. With my wife and I were both working high pressure jobs (attorney/public school teacher in Chicago) and being far away from our families and social supports and the demands at home of being "on" with the kids really weighed us down. The winters were the worst. You feel forgotten by the whole world.
But as so many have mentioned, around the time both of the older kids started school, things got so much better. Not only were the kids more independent, but we just got better at parenting. Knowing when and how to invest time in your kids and when and how to step back and let them play was key. When our third was born we were lucky enough to be able to go down to a single income. And with childcare closed up for the first year of the pandemic, I got spend every day with my youngest. It wasn't always fun, but what they heck else did I have to do? I was no longer working, so that stress was gone. We would take long walks, learn our letter, wander the malls and shopping centers, he'd even do yoga with me in the living room. I'm so much closer to my four year old than my other kids who literally had to endure their stressed out parents during those tighter and leaner years. I feel bad they didn't get the best or most attentive dad during those days because of the pull from everything else, but I'm trying my best to make up for it now by giving them my undivided attention after school and on weekends. My oldest loves going movies, so we hit the theaters once maybe twice a month on Saturday mornings, just him and me and then we go to Five Guys and discuss. I'm really hoping he will want to continue this even as he pulls away in the teen years. The middle kid loves soccer and climbing. I make every single game a priority. And he's old enough now to boulder so we go on Monday nights, just him and me. The four year old still gets most of my time, but I've taught him to ride a bike and to swim this year which is so much cooler than playing Paw Patrol (again). Being a parent in the US is terribly hard especially if you lack a local support system. We did our best to stay in the moment and be excited about the things our kid was excited about. Now we see that our kids are actually pretty cool people, not just needy little life-suckers.
Things that got us through...
My wife and I agreed that no matter how rotten the day was, when one of us walked through the door we would be excited to see the other and to welcome them home. And do you know what? Now all three of my kids light up when someone in our family comes in. It's so stupid and over the top, but I get so excited about coming home from my run or the supermarket now.
Hiring a cleaner to come once or twice a month. We were able to maintain a satisfactory level of sanitation with a vacuum and a thing of Windex, but never had time or patience to do the deep cleaning around the house. Outsourcing that was worth it.
Packing a small shoe box with Legos (just the bricks, not the figures or sets because the kids fight over them) and keeping it in the car. When we'd go to a restaurant or had to wait in line somewhere, we brought the Lego bin with us. The kids would sit and build and let my wife and I breathe and talk and even enjoy the meal.
Along with this, making a kid and grownup friendly car playlist. Even now, all three boys add music to it and it makes the traffic so much more enjoyable to hear both a preteen and a four year old singing Coldplay or Imagine Dragons in the back seat.
Paying for private swim lessons on Saturday mornings when the kids were young. Not only did we not have to worry about pool safety from age 3 on, but we usually got them to take a nap in the afternoon because they were exhausted.
As far as running goes, sure I slowed down and lost fitness after becoming a dad, but last year I ran a 5 flat mile and 17 flat 5k and 1:19 half in some little local races and had the best freakin' cheering section I've ever had. Try not to just endure the time, do what you can to find enjoyment in it. And when you're in it and feeling low and lost, cut yourself some slack. Take some time for yourself, even if it's just to take a walk. I promise you that your kids don't want you to be unhappy even if they are needy and whiny and sick all the time right now. They just want you to be delighted by them at this age.