Rav Yechezkel of Kuzmir zy”a explains this pasuk in a similar vein by saying that if a person who is going through a hard time complains about his situation and says that it is bad, Hashem replies, “You think this is bad? I’ll show you something that is really bad!” He then sends even worse suffering to the person.
As long as the individual continues to complain, Hashem will send worse pain and suffering. On the other hand, if one strengthens his emunah and accepts that whatever Hashem sends him is for his benefit and is actually good, Hashem replies by saying, “You think this is good? I’ll show you something that is even better!” He will then shower the person with kindness and compassion. The more the individual praises Hashem and thanks Him for the goodness, the more goodness He will send.
Accordingly, the pasuk is saying that when a person says “heitiv” – if he says that what Hashem gave him is good – then Hashem says “aitiv imach” – I will do even more good for you.
