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

-James E. Faust 

  What he is trying to say is that to not have problems, just choose obedience. Since your being obedient, you no longer have to be irritated about facing the consequences. For example, if you aren't obedient, you stress out because you know you did something bad. Also, you hsve fear you might get punished and have to face the consequences. But, if you choose to be obedient, they you won't have to deal with all of this "irritation". Also,he is comparing obedience with blocks. For example, if you choose the right, you make it a building block. But if you choose the wrong, you'll come upon a stumbling block. A stumbling block makes your life harder. A building block helps you build up in a good way. Choose The Right, choose obedience!