In Mesillas Yesharim, the Ramchal stresses the importance of proper preparation before performing mitzvos:

“One does not enter into the performance of a mitzvah suddenly without composure and without having thought about it beforehand. Rather, one collects oneself and prepares his heart in calm, so that he thinks in a deliberate and organized fashion about the mitzvah at hand. Thereby, before he starts, he has full knowledge of what he is about to do and for whom he will be doing it. This mental and emotional preparation makes it easy for him to rid himself of any ulterior motives for performing the mitzvah, and the proper and desired motive will become fixed in his heart.”