Point system. Kids love a point system. Stickers, whatever rewards you want to give them ... create a point system. Use a point system in groups. Groups police themselves.
I had a 3 chance system. Write the name on the board. Two ticks next to your name and you get a consequence for your actions: expulsion, extra homework, whatever.
Talk to other teachers. Ask them how they deal with these students. Adopt the classroom management styles that others have. Walk in their shoes until you develop a style of your own.
We had school agendas. Students hated me writing in their agenda because that meant Mom & Dad would see they had misbehaved.
... There is so much more.
As for stress: E-X-E-R-C-I-S-E - run, walk, jog, bicycle, swimming, snuggling, whatever it takes - be active.
But be practical, teaching primary and secondary is not for everyone. Don't accept work just because you are hungry. Is this a job or a vocation for you?