It's the long game vs. the short game.
The dream is the long game. It's the accumulation of your 'grind-it-out' day-to-day work into a life that works for you and a process that makes you happy and successful. The grind is a sprint. The dream is a marathon. But, in order to complete a successful marathon, you're going to have to know what it feels like to work up to it.
Just like it's not sustainable to continue to sprint all day every day, you won't get to where you want to go if you are always grinding. But that doesn't mean you should never grind. Know when to sprint, when you rest, when to pace yourself.