Despair Leads to Kefirah

Rav Moshe of Kobtin zy”a once saw a chasid who looked very depressed. He said to him that this pasuk can be translated to be saying: “V’haya im shachoach...” If one forgets “v’haya”, meaning that he forgets to be happy (as the word “v’haya” always connotes happiness). “Tishkach es Hashem Elokecha.” He will come to forget Hashem. This is because sadness leads to despair, which ultimately leads to kefirah.