"when obedience becomes our goal, it is no longer an irratation; instead of a stumbling block, it becomes a building block ." - James E. Faust
To me this mean that once you get use to being obediant it becomes simple to you. In other words when you are obediant it becomes like a part of you and then you get use to. You get so use to it that it's something you automaticaly do. So what i think Mr. Faust is trying to say is that to practice obedience and it will become a natural part of you. That's what he means when he says  that it won't be a stumbling block but a building block, because you can't stumble on something that your great at. so practice obedience and it will get easier to follow the rules. It may be rough to be obedient but once you get the hang of it will be a piece of cake. Don't pressure yourself in trying to be obedient from thr next day to the other. Try be doing small steps, as in following the rules one rule at a time.Remember practice makes perfect and if you try to be obedient you will become an expert on it.
In the words of James E. Faust "when obedience becomes our goal, it is no longer an irratation; instead of a stumbling block, it becomes a building block ." i leave you to think about it.
Example : i sometimes get irratated in being obedient but im going to try. I believe that what james is saying is true. I can prove this by remembering my cousins. They always listen to their parents and their so use to it that it's who they are now.