In my opinion:

When you are showing your One that His pleasure comes first, when you are pleasing Him beyond your own pleasure. Obeying Him when you don't feel like obeying, getting up in the middle of the night to get him a glass of water cause he is thirsty, or accomplishing everyday tasks because you know it pleases him and in pleasing him you find your pleasure. And finding your pleasure in serving him and his needs, That is finding your submissiveness, that is what brings you the peace and that liberated feeling of being on your end of the leash.