Is it true that whoever has not fallen ill is forbidden from entering Paradise?

We have not come across any hadith indicating that a person should ask Allah to afflict them with trials. Rather, you should ask for well-being (al-afiyah) and praise Allah for it, as it is the greatest blessing after faith. The Prophet (peace be upon him) said: "Ask Allah for pardon and well-being, for no one has been given anything better than well-being after certainty (of faith)." There are indeed hadiths about the virtue of patience during trials, such as the Prophet's saying: "When Allah loves a people, He afflicts them," and "Whomever Allah wishes good for, He puts him through some hardship." The purpose of these is to encourage patience after a trial has occurred, not to encourage seeking trials. So, praise Allah for well-being and utilize your health and youth in righteous deeds.