I have an English Cocker Spaniel that once gave birth to three beautiful puppies. What had taken me 1.5 years to teach to their mother took me virtually no time to teach them.
It was incredible. And also, a lot of fun! :)
But I think there is a correlation there with many of the points OP makes in his note. The dog won't train him/herself so you must dedicate yourself to some sort of schedule in order to reap any progress; if you won't, who will? This is well aligned with the first point OP makes.
I found the early period of my dog's training to be, by far, the most rewarding both in intrinsic and extrinsic manifestations. I now have a very well behaved dog and I've seen numerous latent benefits in my health and well-being as well.
Ill concede that the most important change I've seen in myself has been a decrease in selfishness and an overall increase in empathy. I am often doing things for my dog simply because I put myself in his shoes (e.g. making sure to take him out right before he goes to sleep, because I know how uncomfortable it is to try to sleep with a full bladder). This seems juvenile and seems like it should appeal to anyone with common sense, and it probably does, but for me it was an important lesson that translated universally across my current life experience. A lesson I likely wouldn't have learned without my dog to teach me.
Challenges include games and tasks, and all that. These dogs need "work" to feel alive.
I don't mean to discourage you at all. I've had 2 dogs, pretty much raised the one by myself, and don't regret it at all but I did want to give that insight so it doesn't go over your head! If you have any specific questions about what goes into raising a puppy, feel free to reply here or email me at [email protected].