A push is really anything beyond asking staff to plan, assess, grade, give feedback, and respond to parents needs. Those are their primary jobs. Anything more is a push, managing when and how much to push is key to keeping an environment where staff feel like the work they are doing is making a difference vs. just making days go by.
When pushing you must always keep in the back of your mind that school is for some 30% of their overall life and maybe for others 90% of their lives. This needs to be understood as the outside of school life certainly affects the inside of school life.