The identity shift nobody tells you about
Before kids I was defined by my job, my hobbies, my accomplishments. I was ambitious, driven, always had a five year plan. Became a dad and realized all that stuff doesn't matter the way I thought it did. Now I'm defined by whether my kids are happy and healthy and that used to seem like settling to me. Weird thing is I'm more fulfilled now even though I have way less freedom. I guess I just changed what I want from life. Took me two years to stop feeling guilty about caring less about climbing the ladder.
This is the thing nobody really prepares you for. You go from being the main character of your own story to basically being a supporting actor in everyone else's. It's a big adjustment.