Thank you for your question (though, I must admit, it’s a tricky one!).
When working with inexperienced teachers, for example on a CELTA course, it’s really rewarding seeing them develop as the course progresses and putting their learning (e.g. from input or feedback) into practice in the classroom.
As far as in-service goes, I really enjoy getting the opportunity to work with teachers from a variety of backgrounds and with experience of different learning and teaching contexts and learning from them too.
Certainly not an exhaustive response to your question, but rather just a couple of examples of what I enjoy about the role.
Looking forward to working with you.
All the best,