This Hadith was said after the Prophet [pbuh] was shown glimpses of Paradise and Hellfire.
He [pbuh] saw the immense rewards and the terrifying punishments, realities far greater than our limited minds can fully grasp in this world.
The Messenger [pbuh] knew the severity of the grave, the questions of the angels, the terror of the Day of Judgment, the Bridge (Sirat), and the eternal consequences of our actions.
If we truly understood what awaits us, our laughter would turn into tears of fear and hope...โคต๏ธ