I wish it were always true that Orthodox Jews keep the Mitzvot because we see the truth and the beauty of them. Unfortunately, I think in a significant number of cases people keep them because that is the way they were "programmed" and do not really think about why they are doing it too much. However, ideally we should study Judaism's teachngs - the Torah and Mitzvot - and hopefully come to the conclusion that they are true and we should keep the Mitzvot out of conviction and understanding.
