The Laws of Prayer /The Blessings of the Shema (59)

1. One must recite the Shema with a feeling of awe, fear, trembling and sweating, by concentrating when he says “With all your heart” that he is willing and ready to give away his life to be killed to sanctify the Name of Hashem. (Shulchan Aruch and Mishne Berurah 61)

2. A person must recite the Shema every day as if it is a new commandment from the King. He should consider in his mind what would happen if a king of mere flesh and blood would send new laws and statutes to the inhabitants of his kingdom how everyone would read them with fear and awe. It follows that he should read the Shema slowly and thoughtfully, not in haste and quickly and with a muddle. (Shulchan Aruch and Mishne Berurah ibid)