... you may want to suggest they aim to teach a second subject too.
As the graph shows, there's a massive oversupply of trainee PE teachers and an undersupply of most other subjects. So if your aspiring PE teacher is competing for a job in a good school, the school will be looking to see what else they can teach alongside it! PE teachers who have second subjects that are in the shortest supply will be in a much better position than those who don't.
I'm saying this as someone who knows a couple of new PE teachers who are struggling to get the jobs they want, and also as someone who works in one of the many good schools that are struggling to recruit teachers in some subjects.