When he is in his thirties, he is usually healthy. Why did he die suddenly?

More than 30 years old, but people often ignore health. I feel healthy and don't need a physical examination. I don't know that only about 10% people in social surveys belong to extremely healthy people, and as many as 80% people have a certain degree of sub-health. He looks healthy in his thirties, but his heart and brain may be in danger, especially cardiovascular diseases such as cerebral hemorrhage and myocardial infarction. Most people who die young have congenital diseases, most of which are invisible, or the family inheritance is unwilling to disclose.