Dogs are very adaptable and have adapted to living and working with humans over the many thousands of years of domestication. If the bond between the animal and the owner is correct, consistency, clarity and patience are sufficient in dog training so that the four-legged friend adheres to the desired rules.
However, we humans must not forget that our animal friends still have their instincts. It would be the wrong way to react to the dog's unwanted behavior with toughness and coercion.
"There he has to go through!": Error or truth?
As long as two strange dogs play peacefully with each other, you do not have to intervene. But if there is a fight or bullying and your dog is afraid, he needs your help. In such situations, if your four-legged friend is looking for your protection or the other dog is physically superior to him and plays too wildly, it would be a mistake to say "He has to go through this!" dismiss. This would not lead to hardening, but would increase or trigger your dog's anxiety and insecurity. If he then notices that he cannot rely on his caregiver at moments that make him feel insecure and stressful, your attachment to each other suffers - and this in turn makes dog training difficult.
Bullying among dogs: how to protect your dog
Unfortunately, there is occasional bullying among dogs when several four-legged friends meet ...
Dog training: adaptation yes, toughness no
If you want to achieve toughness through dog training, it is better to start very small and get support from a dog trainer if necessary. This is advisable if your dog has already developed an anxiety disorder. Systematic desensitization is the technical term for when your four-legged friend gradually gets used to an anxiety-causing stimulus. For example, if your dog is afraid of a thunderstorm, it doesn't make much sense to send it out in the lightning and thunder to harden it. Instead, you should gently accustom your little scaredy rabbit to the sounds and offer them a safe haven during a thunderstorm in the house.
Dogs have to adapt to many things when living with their humans that do not correspond to their natural instinct. They learn to walk on a leash, eat the food they are given, understand commands and behave in public. That alone demands a lot of frustration tolerance, impulse control and willingness to learn. It is unnecessary to ask him to endure and endure situations that can frighten him or that can even be dangerous.