I've appreciated this thread and the many perspectives. I can relate to an extent to pretty much all the posts. I believe running is the greatest metaphor for parenting and life itself.
While I know the thread is about parenting (so perhaps what I'm about to write is accepted as a given), I would suggest focusing on the marriage relationship first. That by itself will help steer you down the right path and be extraordinarily helpful during the more difficult times. Doing a hard interval workout by yourself feels miserable - almost impossible. Sharing the track with another who is doing a similar workout at the same time is a little better. Actually doing the whole workout together with someone else is better yet. Or maybe a better analogy would be that focusing on the kids (without first working towards having the marriage relationship in the best health possible) is like running the workouts without having the consistent training behind it.
Some parents are going to be great with toddlers while others are better with teens or even young adults. It's ok. Do what you can in the time and place that you're in. Avoid comparing yourself with others in unhelpful ways.
Relatedly, there seems to me to always be a prevalent almost omni-present sentiment or message floating about that says "you're less than". Don't give that lie any quarter and especially don't project it onto others. I'm in no way advocating laziness or negligence, and by all means go for the best. Yes, you can do things that have "worth" but you are not the sum total of the things you do or have achieved. When you start believing you're "less than", or the preconceived expectations (often unrealistic) that you've constructed in your head are a struggle to meet, then it can be a downward spiral under this heavy and completely unnecessary weight. You can become like the good solid runner that way underperforms at the meets... a classic head-case. Relax and just run, baby! You can do this.
Figure out "truths" you are onboard with and then live accordingly. If you're going to be swept with the current of the river, it would be better to paddle along (sometimes furiously) to steer and avoid banging into things. Another "lie" that I think perhaps a lot of people buy into (maybe subconsciously?) is "you can have it all" (or have it all all the time :)). Parenthood is not for everyone, and I don't say this to minimize their choices. In fact, many on this thread have mentioned that they're glad they're not (and I get it). From a strictly financial ROI perspective, having even 1 child is a horrible decision.
Very quickly, hiphoppingworm, thank you for your earlier reply. Your wife sounds like a keeper :). Happy birthday in this upcoming week.
A short earlier post by RGARC2 said at the end to "Try to stay positive and focus on what you have to get through the hard. Keep going." I think this is golden. Choose to see your wife and kids and your place through a grateful lens, and then this habit will start to come naturally. A side benefit is that they will start to see you similarly. I don't mean to be overly pollyannaish, but you are not a powerless victim to your feelings. You can change your feelings by what you tell yourself over time.
Middle Aged Female No Kids, I don't think you should cry over not having kids. You're simply on a different path that is meaningful and beautiful in its own way. To answer your questions, 1) My wife is a stay at home wife, but I would say she works full time :). Besides the family stuff, we own a fledgling business, and it would be a massive understatement to say she contributes. 2) I make it a practice to avoid speaking for her, but she doesn't do the letsrun forum. As a mom of 7, she would tell you that whoever is saying to you "I'm tired but I didn't know what happiness was until I had kids" is feeding you some grade-A garbage. Maybe they had an inadequate view of life before they had kids, or maybe they are attempting (rather poorly) to justify their current position to themselves. We love our kids, yes, and we're thankful for them and the good times, but they are not the be-all end all of life. I am sure if you caught my wife at the right (rare and very difficult) moment, she would indicate that maybe life would have been better without them (or without me (lol))! But that's not reality. We have our situation and you have yours, and both can be challenging and "fulfilling" in their own ways.
To all, I wish you well in your journey and race of life. May you run well.