One who trusts in H'shem does not worry or get excited about the future as he knows it is not in his control. "Do not worry about tomorrow's trouble for you do not know what a day may bring. Suppose that tomorrow he is no more he will have worried about a world that is not his".
pg 455
Nefesh HachaimThe Yetzer Hara may confuse you by trying to get you to an "exalted" fear of GD and not fear of punishment. He may try to convince you that being afraid of punishment and embarrassment is a sin. This may lead you to sin if you are not in the state of exalted fear of GD
Prologue to Gate Four Chapter 8 pg 130