There’s no mystery here. It’s simply a matter of the physics of time. There are only so many hours in a day and days in a year. Time is a standard metric for everyone (at least until time machines are invented).
But the greatest defining factor of productivity and fulfillment is how we spend the limited time we have. No, this is not a matter of living life in “top gear” 100% of the time; it’s a matter living life “engaged” as much as possible. Quite simply, this means maximizing time spent doing things that make you feel alive. It’s been said many times before: life is too short and too long to spend it doing too many things you don’t like to do.