The First Thought of the Morning
On the pasuk "And the frogs came out [of the Nile] and covered all the land of Egypt" (Shemos), Rav Menachem Nachum taught that this alludes to the very first thought of the day. When we wake up each morning with holy thoughts of avodas Hashem (serving Hashem) at the forefront of our minds, and we get out of bed and attach our thoughts to Hashem with gadlus hamochin, an expanded awareness of the exaltedness, greatness and awesome majesty of Hashem, this becomes the theme for the rest of the day. The whole day follows its beginning, and the morning's thoughts influence the rest of the day. If we start the morning right, it is much easier to serve Hashem for the rest of the day. This is hinted at in the pasuk. צפרדעה (frog) is a compound word, hinting at צפר, morning, and דעה, thought or intellect. When we concentrate our first thought of the morning on Hashem, it covers the entire land of Egypt. מצרים is also a compound word: מצר ים, the oppressors, the forces of tumah (impurity) and darkness. Once we begin the day with holy thoughts, with our minds attached and bound to Hashem, it is easier to cover over all the forces of evil and the klipos (husks of impurity), and to serve Hashem better for the rest of the day.
Source: M'Peulas Hatzaddikim, cited in Beis Mordechai to Sefer Hayachas Chernobyl, p. 24