I think there is a big difference between disappointment and discouragement.
We will all be disappointed at one time or another. That is totally fine. I was disappointed this morning, in fact, when we had a planned lesson fall through. I usually get disappointed when planned lessons fall through. I do because I know the joy and happiness that come from accepting and living this gospel. So it is hard to keep going when I see others not accept it. I get down and sometimes I get a bit frustrated. But we can't let that get to us! God allows disappointment to better us. To help us to learn. On the other hand, Satan is the source of all discouragement. He is the one telling us that we should quit when things aren't working. He is the one trying to make us miserable and trying to tear us apart. Why does he do that? Because he is jealous of us. He doesn't want us to come closer to Christ. That is why living the worldly life is easy while following the path of God brings challenges and hardship. It is inevitable. But if we allow discouragement to take over, we are allowing Satan to win. And we can't allow that to happen! Discouragement will lead to bitterness and anger.
We are in charge of our own happiness. We decide our reaction to others actions and the situations that we are in. We can't control situations, but we can control our reaction to them. We have to be stronger than Satan. We can win through following Christ and fighting through the situations that we are in.
All of us encounter disappointment in one form or another. It might come through such circumstances as unmet expectations, elusive career opportunities, failing a test, being disqualified during a try-out for a school play or athletic team, or being excluded from certain social functions.
Disappointments can be seen either as a prelude to continued failure in our lives or as occasions for great personal growth and even the beginning of truly outstanding performance.
All human beings experience disappointment. If this hard fact of development were not so, it would be very difficult to explain the joy of personal growth that often follows setbacks. Our challenge is to maintain balance and perspective through inevitable disappointments.
Let us use our disappointment for good.For strength and growth vs. failure. I know that through Christ and His Atonement we can all find that peace and hope through any trial.