"When obedience becomes our goal, it is no longer an irritation; instead of a stumbling block, it becomes a building block."
     -James E. Faust 

This quote is trying to say that obedience can be something hard, irritating but if you take obedience as a goal, it won't be an irritation anymore. If you get use to obey, it won't bother you to obey anymore. 

"The key to freedom is obedience. The more obedient we are, the more freedom we have."
       -Boyd K. Packer

This quote is trying to say that if you are obedient, you will be awarded with Freedom. If you are more obedient, then you will have more Freedom. If you don't obey, you will be punished and you will have no Freedom.