In previous generations, it was the custom to wear Tefillin throughout the day. Even after Davening, Tefillin was worn when going about one's business, in the street and at home. However, in later generations, Yidden had lost a certain degree of commitment to the Mitzvah of Tefillin (along with other Mitzvos). Rebbi Shimon Ben Elazar said: Mitzvos for which the Jews gave up their lives - in the time of a government decree - are still upheld with a strong commitment by the Yidden, such as: Bris Milah and not serving idols. And all those Mitzvos for which the Yidden did not give up their lives, still lacks commitment and is "weak" by them... such as Tefillin, which is still "weak" by the Yidden. (Shabbos, 130a)








