Where we're from, being a lifeguard in the summer is really fun. Kids who swim in an indoor or outdoor pool all want to become lifeguards, but it remains a summer job. It's the same for the trainers who teach kids aged 8 or 9. The job gives them a bit of pocket money while they are at school. Aside from them, few people are interested.
It's a difficult situation. We could probably hire other trainers who do not have all the swimming knowledge, but who could stay longer than them. But we would prefer trainers who have a very good knowledge of swimming. It is preferable to see them train and demonstrate their skills to the children than to hire people who know nothing about swimming.
So there is major turnover. Every two or three years, we lose our trainers and have to replace them with younger people going to school. Having said that, we prefer having them than other people who do not have the same knowledge.