I can definitely relate. I've taken week-long solo vacations (with my wife's approval!) just so that I can code without distractions.

I don't have kids, but given that I can easily work 6-8 hours straight on completing a feature, I have to curtail it to maintain a high-quality relationship. (I also weightlift, which can take up a lot of time.)

It's very difficult for me to get into the zone in three-hour spurts, and coding at night at the cost of my sleep is something I've retired. Shoot, a three-hour work session might be me trying to fix _a single bug._

Regarding "the hump," the show _Ted Lasso_ actually does a great job of describing this. A star player retires as they realize that they are no longer as spry as younger talent. Part of this show is about how they choose to deal with it.