Another quote from Seneca:

Everyone hurries his life on and suffers from a yearning for the future and a weariness of the present. But he who bestows all of his time on his own needs, who plans out every day as if it were his last, neither longs for nor fears the morrow. For what new pleasure is there that any hour can now bring? They are all known, all have been enjoyed to the full. Mistress Fortune may deal out the rest as she likes; his life has already found safety. Something may be added to it, but nothing taken from it, and he will take any addition as the man who is satisfied and filled takes the food which he does not desire and yet can hold.