Rejoice in others' successes

I have recently been reading a book called Stargirl by Jerry Spinelli. It is a wonderful book and I highly recommend it. Stargirl is a very unique person. She is very much an individual. She sings happy birthday to people in the cafeteria daily, she dances in the rain unexpectedly, she leaves treats on students' desks, is always aware of other students' problems in the high school, and many other strange things. The students begin to find her amusing and ask her to be a cheerleader. The funny thing is, this is what makes people actually start coming to the games! But it also happens that when the other team scores, she cheers just as much for them. She is happy because they are happy. The other students begin to hate her for that, but she can't understand why.
As a missionary I would sometimes struggle with the idea that other missionaries would be more successful in some areas. For example: we were having a special conference just for Ecuador with Elder Nelson and we were told to bring investigators. We worked really hard to get investigators there, but nonetheless, there was one companionship that kicked our trash with the number of investigators they had brought. I being a leader felt I had failed at being an example. I felt embarrassed that I couldn't keep up with other missionaries in that instance. I recognized those as very prideful and wrong feelings, but I still felt them. I felt like I wanted to be the best missionary ever, and if someone showed me up as in the case of the special conference, I was not being a good missionary. Tough feelings. Very wrong feelings.
As I reflected, knowing very well I was having inappropriate ideas about success in this moment, I came across a scripture on one of our mission trips to the temple that really helped me understand how I SHOULD HAVE been feeling! It is in the Book of Alma, Chapter 29, Verses 13-14. It says: "...yea, and that same God hath called me by a holy calling, to preach the word unto this people, and hath given me much success, in the which my joy is full. But I do not joy in my own success alone, but my joy is more full because of the success of my brethren..."
Let's be happy when others do well and have success!