I don't have a solution for you other than to talk to/at them. But you have to balance scolding, motivating and length of talk based on what you feel they need at whatever moment you're in. It's a fine art.
If you're young just keep at it, being mindful of what you say, how you say it and how long you say it. Then be mindful of how effective it was.
I firmly believe that's one of the many things we teach; how to manage emotion/mood and keep focus throughout distractions. In this case, INTERNAL distractions. Think about times you showed up to work angry or sad but had to 'suck it up' because your students needed you to lead them through rehearsal.