The term "air hostess" is a popular nickname, but more objectively it refers to the women among the flight attendants. Due to the split in China's civil aviation industry in 1992, there was an unprecedented period of rapid development afterwards. Many flight attendants were recruited during those years, so they tend to be relatively young. However, being a flight attendant is absolutely not the "youth-dependent job" that most people imagine it to be. Some of them already have sons who are in college! It's just like being a pilot.
They undergo a physical examination every year. Aside from the strict recruitment process and rigorous initial medical check-up, the annual physicals afterwards are quite relaxed with fewer items to check. As long as they pass the annual medical examination, they can continue flying. Generally speaking, for those who reach a certain age and choose not to fly even though they passed the medical examination, there are usually two scenarios: one is that they no longer wish to continue working as a flight attendant, and the other is that they have moved into a leadership position!