He first describes how there are two divisions of "zeal" 1) before you start the Mitzvah - you should start as soon as possible and not push it off 2) once you already started you should finish it as soon as possible (of course he explains that this should NOT be in order to "get it over with" but rather for fear that it won't be completed).
he then says:
QUOTE
....The man whose soul burns in the service of his Creator will surely not idle in the performance of His mitzvoth, but his movements will be like the quick movements of a fire; he will not rest or be still until the deed has been completed. Furthermore, just as zeal can result from an inner burning so can it create one. That is, one who perceives a quickening of his outer movements in the performance of a mitzvah conditions himself to experience a flaming inner movement, through which longing and desire will continually grow. If, however, he is sluggish in the movement of his limbs, the movement of his spirit will die down and be extinguished. Experience testifies to this....
Which I take to mean that even if one does not really "feel" any zeal, if he acts like he does, he will eventually create it by himself and have it, which is interesting in itself but would this apply to other things besides "zeal" as well, for instance if one were to act as if he is pious and be strict in things he does (even if he does not really feel that he is on that level) would he in the end become like that? (I am NOT asking about someone who is just doing it to show off or to fool people in to thinking he is pious, I am asking about someone who is doing it in order to eventually reach that level) does it work that way?is this a commendable approach ?

I disagree.