From this article about Rabbi Levin Zatza"l
Rav Levin’s rebbi, Rav Doniel, once asked, “Is man jealous of the wings of an eagle?” As the question sunk in, he responded, “No. Man is not jealous of wings. In fact, if a person would grow wings, he would be a baal mum; there would be something aberrant about him.” Wings belong on birds, not on people. “The same,” Reb Doniel explained, “would be the case if a person receives anything that which he is jealous of. He would also become a baal mum. If he really needed that which he covets, Hashem would provide it for him. Since he doesn’t have it, that is a sign that he doesn’t need it. Everything extra is a mum.”
Imagine if we lived like that. Imagine if we had the strength and belief to live that way. We would be so much happier and calmer. That is the life of a Kelmer, of a baal mussar, of a ben Torah.