Commands vs. Labels
It's a natural thing that people do: they start giving their dog a "command" before the dog knows what the command means. Some dogs are quick learners and they pick it up right away. The problem I see is that many people point at their dog (why?!) and say "SIT!" about 20 times when the dog has NO idea what "sit" even means. The more you say a word while the dog is confused, the less meaning the word has. It's like those Peanuts cartoons when the teacher is talking and it's just "Wah, wah, wah, wah," aka nonsense.
Instead, let's help your dog actually learn the language by first showing them the behavior! A good rule of thumb is to shape everything with food. Then, once your dog is reliably performing the behavior, LABEL it. Don't "command" and demand, teach your dog. They love to learn, as learning is work, and dogs love to work. This video is the perfect example of what I'm talking about. At minute 3:35, when the trainer starts using the "Whoa" command, he's simply labeling a behavior that the dog is naturally performing while in a state of drive. This should be your gold standard of training.
Test Your Verbal Commands
Here's a test for you, does your dog really know his commands? While it's best to teach every command by labeling the behavior and using food for multiple repetitions (and I'm talking hundreds, if not thousands), eventually, you want to see if your dog actually knows what you're talking about. Now, without food, ask your dog to perform a behavior. Will they do it? Or are they still "hooked" on the food or your body language?
Another test: can your dog perform the behavior around distractions? Go slowly and work up to this! Don't rush it. Start with those hundreds of repetitions in your own yard, or another low-distraction area. Get a good foundation going. Then, slowly start adding stimuli and see what happens. If you work at a proper pace, your dog should be able to channel the energy (level of arousal) he derives from the distraction into the training. This takes time and patience. It's best to work for weeks or even months building a strong foundation away from highly stimulating situations, and then take your training out into the field.
This is because you want to set your dog up for success every step of the way. The more reps you get in that are successful, the more solid a foundation you are giving your dog. The more you practice unsuccessful reps, the more your training slowly falls apart.
Can I Discipline My Dog If He Doesn't Listen?
No! If your dog failed to perform, you made a mistake. Old-school trainers may tell you that the dog must respect the owner, and once they see the owner as "alpha," they will perform behaviors out of respect. If you had a boss who expected you to show up for work for no paycheck, and then started shouting at you for poor performance, how long would you stay at that job? Not long, I'm guessing.
Your dog needs a paycheck, not discipline. That can be food, or better yet, a toy! Eventually, it can also be affection and praise, whatever floats your dog's boat. If your dog isn't performing, he either needs a raise (better food/more interesting game of tug), or he needs his boss to be a better communicator.
Dog training isn't easy, it can actually be extremely tedious! We're not usually speaking the same language as our dogs. They are basing their behavior on our body language, the potential reward, and our general emotional state more than anything. And then we get frustrated because they don't seem to understand our verbal commands.
Remember, if your dog doesn't understand or can't perform, it's your job to figure out why, not to punish "misbehavior." For inspiration, I highly recommend watching this video: Old Dog.