Mesilat Yesharim
Likewise, they said in the Midrash (regarding the mother of Shimshon): "'and the woman made haste and ran...' (Shoftim 13:10) (Midrash:) this comes to teach that all the deeds of the righteous are done with haste". For they do not allow an interruption of time to elapse - not before beginning the Mitzva nor in completing it.
Mesilat Yesharim
When a man comes to realize as truth the great value of the Mitzvot and the greatness of his obligation in them, his heart will certainly be awakened to the service of G-d and he will not be lax in it.