I would agree that there are times when physical punishment might be the best. Unfortunately, there have been enough adults in positions of authority that abused that privelege over the years that that option has been effectively revoked.

Kids need to know the rules. They need to know where the boundaries are, and then they will attempt to push the limit-wherever the limit is set. If you set consistent, reasonable standards and follow up with consistent reasonable punishments for misbehavior the kids can figure out what is expected of them. The punishment has to fit the offense, and be something that makes sense.

A parent or teacher losing control of themself will not inspire a child to behave.

Our kids knew beyond a doubt that I would not hesitate to give them a spanking if they deserved it. Strangely, I never had to.