The filling is made up of moments where you are fully alive, in the present, letting the universe experience itself through you, but sandwiched between rueful regret and unfulfilled desires.
No one can just have the filling, but there are ways to get a lot of it. And when you take a bite at it, the sandwich occasionally folds into itself, unable to differentiate the bread from the filling, unable to tell anymore whether you’re aching or alive.
And that’s okay. That’s the meal.