Wife and I decided to have a kid a when I was around 40 (she's younger) as our daily life seemed to lack real purpose. We never had a strong desire to be parents but another several decades of work, netflix, sleep with a few vacations and nice restaurants sprinkled in to break up the tedium just didn't sound fulfilling after having done exactly that the previous ~15 years. It also coincided with some other health related stuff that made us really have to evaluate a now or never type decision on kids. We decided we'd probably regret it if we didn't.

I'm still somewhat aware that I'm having a mid life crisis but it's more of a feeling of wanting to enjoy my kid being a kid before he outgrows me and nothing else really matters. I don't chase money or work accomplishments, never really have, but they do pull at me and now I push back a lot more. So a massive shift of prioritization is in place where I prioritize my social calendar (or kids) over my work calendar at all cost. I really have no relationship with my dad (by choice, but with reasons) so I now often think that is my primary objective to make sure my son wants to keep me in his life as an adult. So in a large part I'm just trying to not repeat the mistakes my dad made with me... but I also really enjoy my kid and want to spend time with him, so it helps.

Anyways, good luck with finding yourself on the other side of the hill. Maybe my story will help you in some way.