I've spent my whole life training horses, and I think the same principles apply to training just about any animal.
Animals learn from repetition. You give them a cue, and expect a certain behavior. With repetition, it becomes a habit, almost an instinct.
The trick is getting that behavior to take place enough times that they associate it with your cue, and make it a habit.
Animals have a comfort zone just like people. If you take them out of their comfort zone, they will do something to get back in it. You don't have to inflict pain to take an animal out of their comfort zone, and it definitely should not be the first method you try everytime.
If you go straight to inflicting pain, you have no other recourse. If it doesn't get the behavior you want....you can't resort to anything else. It also ruins the animals focus. Because you are constantly inflicting pain, the animal is going to be under stress, its going to be a lot harder to get it back into its comfort zone. If it can't get there, it can't associate that with the behavior you want.
You also have to show the animal how to get back into its comfort zone. They have to know what behavior you're looking for. Then you keep pressing them until they give you that behavior. They have to have an outlet.
Here's an example.
I just started working with a 3 year old colt, that has been handled by people alot, but has never had any serious training. I need to saddle break him. The first day, I went in his stall with him and he immediately whipped around into a corner and presented me with his tail end, ears pinned back like he was planning on kicking me if I went any closer. This isn't acceptable behavior, I expect him to face me and let me come to his head when I go in the stall.
So the behavior I want is for him to turn around and come to me. The cue I'm going to give is to stand in the corner of his stall and calmly talk to him.
So now I have to do something to make him uncomfortable while he's there in the corner.
I could haul off and whip him with a lead rope, but this is probably just going to make him see how small he can get and how far into that corner he can go. It makes him uncomfortable, but doesn't show him what behavior I expect, he doesn't have an outlet.
Instead, I take a lasso and swing it slowly, and toss it over his head. This generally scares the heck out of them and makes them very eager to leave the corner. At the same time, I now have the rope around his neck and can use it to guide him. I can flick the coil at his rear end if he still doesn't want to move, and I can pull on him so that when he does move he turns to face me. I'm showing him where to go.
So I use the rope to apply pressure until he's standing facing me, within reach. Then I release the rope and stand still for a second to see if he will stand there. If he tries to leave, I go back to pressure on the rope. If he stays there, I slowly reach out and try to touch his neck or face.
When he tries to leave, its not the behavior I want, so I go back to pressure on the rope. Eventually he lets me touch him, and I stand there and pet him and let him know this is what I want. I stand there and pet him and don't worry about doing anything else until he's calm and stays there willingly.
After a couple times, we've established a pattern of him being uncomfortable in the corner and comfortable facing me, letting me pet him. Now when I open the stall door he comes over and meets me.
Following this principle is that fastest most effective method I've found. Simply rewarding good behavior doesnt' work, because you spend too much time waiting for the good behavior to take place, and there isn't enough consistency in what lead to the good behavior. You have to be firm, and make things happen, but pain the not the first, and certainly not the only tool you use.