I've noticed that it slows back down to childhood levels when I am on a really fun vacation, especially one that involves heavy physical activity and fascinating new outdoor environments. I think the novelty, play, and lack of stress combined are able to 'fix' this.

I am convinced the slowing down is essentially cultural, and is a result of how our lives are different as adults- and can be fixed by understanding this.

I think this can be accomplished full time as an adult by not taking things so seriously, and taking a lot more (not physically dangerous) risks. Go on adventures, don't care about financial ruin, don't care about status or 'careers' and time will slow down.

As a single dad, I can't really figure out how to do that full time given my responsibilities, but can manage it for stretches of time on weekends and evenings.