When reciting the Shema', one must pause a little between "Le'olam wa'ed" at the end of Berukh Shem, and the word "We-ahabta", to make a separation between the acceptance of the Kingdom of Heaven and the performance of the other Miswoth (commandments). When saying the verse of "We-ahabta", one should have the intent to accept the positive commandment of loving G-d, and this is one of the 248 positive commandments.
One should also pause in the first verse between the word "Yisrael" and the word "Hashem", and between "Elokenu" and "Hashem", so that the meaning will be, "Hear O Israel, for the L-rd who is our G-d, He is one L-rd".
In fact, one should also pause between the first verse of "Shema' Yisrael" and the second, that of "Barukh Shem", (i.e., between "Ehad" and "Barukh"), because the essential part of accepting the Kingdom of Heaven, is in the first verse.
(See Shulhan 'Arukh with Rama, 61:14. Kaf Hahayyim, ibid., Oth 48)
Shema' Yisrael, Accepting Kingdom of Heaven