When one wakes up in the morning he should think about the great Chesed Hashem has done for him, by returning to him his Neshama, that was given to Hashem tired and worn out, and now returned new and calm in order to serve Hashem with all his strength. Therefore one should say when waking up in the morning מודה אני לפניך מלך חי וקיים שהחזרת בי נשמתי בחמלה, רבה אמונתך. I am thanking and admitting, to you Hashem, for that which you returned to me my Neshama with mercy.