A way to make us follow them without fail.Our elders say that using turmeric and vermilion are essential for a married woman. Applying Mehendhi (natural one not the cones available in market) good for girls during Ashadam, praying to Tulasi plant gives you happiness, and many things like these by interlinking them with religion or custom. If we observe them carefully and do a little research, these kind of conditions in every religion are meant to make us follow them as they are good for health of our body and mind. If they say that spending sometime daily around Tulasi plant gives you health we may not do it regularly but because they said that it is goddess and gives you luck we are doing it daily out of fear or respect or hope. So is the case with festivals. The Prashad that we offer to God during festivals is made of the naturally available items during that particular season and we all know that nature provides us immunity to the seasonal health problems with its elements like seasonal fruits. So elders prepare dishes with those ingredients which make us immune to seasonal changes and make us to eat in the name of prasadham. My point is all these rituals and customs are meant for our physical and mental health. As we don't do anything out of care they made us do them out of respect and fear.