Notice the pasuk (verse) says, Musar Hashem, beni al tim'as. Hashem turns to every single Jew and tells them, “My son, I'm giving you yisurin (pain). I'm disciplining you for your own benefit. You're my son. I love you.” Don't look at the yisurin that you get as a pain in the neck. Understand that when I give you discomfort, and when I give you yisurin, it's for your own benefit, because I want you to come back. Utilize the opportunity of yisurin.
None of us want yisurin, and we daven for Hashem not to give us yisurin. But when a person gets yisurin anyway, he has to appreciate it. There's good in it. There's what to appreciate. When a person is going through a hard time, when a person is going through pain, when things are not going as planned, although we wish it had never happened to us in the first place, understand that if it is happening to you, there's a big plus to it. That plus is that Hashem cares about you. If Hashem gave you that pain, it means you're not just a random person on the shelf. No, it's because Hashem cares about you, and He wants you to change and come back to Kadosh Baruch Hu (the Holy One, blessed be He).
See, yisurin is a good sign. Yisurin is a sign that you're capable of a lot, and Hashem has high expectations of you, and He wants you, yes you, you, to come back to Him. That's what gives you the pain. Musar Hashem, beni al tim'as: I'm doing it for your own benefit, and don't be disgusted by it, don't despise it.