The Noam Elimelech in the beginning of Parshas Emor interprets Rashi's explanation of the seeming redundacy "Emor Vi'Amarta" -"LeHazhir Gedolim Al HaKetanim" as follows:
Every Yid has times that he feels elevated and close to Hashem - like when he is engaged in Torah or Tefillah or any other Mitzvah - and at these times he feels like he's on top of the world. His mind and heart are open; he feels that he has attained clarity and sees the world in a spiritual light (Mochin DeGadlus). But then, when it's time to go back to the humdrum material realm, he falls from this high level and can't bring that same clarity to his mundane affairs (Mochin Dekatnus). Says the R"R Meilich Zy"a, this is not the way to do things. Rather, one should make sure to "charge his spiritual batteries" to the max when he feels uplifted, in such a way that he will be able to connect his thoughts with Hashem even when he steps down from that madreigah where he was earlier. And that is alluded to by the Ma'amar Chazal which Rashi cites:
"LeHazhir Gedolim" Take heed when you are in an uplifted (big) state of mind, "Al HaKetanim" that one must remain holy even at times that are mundane (small).
Get so much chizuk and put some away for the bleak days. When feeling high, remind yourself to remind yourself how good it feels to be close to Hashem. And what connects us to Hashem more than our little mental communication countless times a day? "Hashem, I cannot manage this by myself, Hashem I know that you can help me, Please take this nisayon away from me, You can handle it" etc. (everyone has their own vernacular with Hashem). Remind yourself that when the YH jumps out from behind a bush, you will talk to Hashem - and not dare to mess with the enemy's guerrilla soldiers. Such a person can, with Hashem's help, KEEP ON TRUCKIN', even in the down-times.