The mitzvah of tefillin is very precious because the Torah itself is compared to tefillin. Therefore, someone who does not put on tefillin because he is lazy to put it on is considered a רשע. The halachos involved in making the tefillin are many and complex, and one should only purchase them from a competent sofer who is a ירא שמים.

When one puts on tefillin, he should have in mind that he is fulfilling the mitzvah of wearing tefillin, containing the four parshiyas of the Torah, which declare the unity of Hashem, and how He took us out of Mitzrayim.