The word Namaskar has two meanings: worship and greeting. When you meet somebody, you say 'Namaskar'. Namaskar means that you are greeting the person, and not worshiping them. Do you see what I am saying? It is used both during worship, and also as a greeting.
Now this has become a big controversy in India because it can give a religious overtone to it.
Similarly, these different mantras are sound vibrations. Sound vibrations affect different parts of the body. For example, when someone is stressed, what is the sound that comes out of them naturally? Hmmmph! This Hmmmph-kara is a mantra.
There is a story in Devi Bhagawatam. It is said when the demons came and attacked, Mother Divine stood up and said, 'Hmmmph', and all the demons got destroyed. All the demons turned into ashes.
Now what does this story mean? When a lot of negativity comes into the mind, there is an inbuilt mechanism in your own body and that is Hmmmph-kara. Take a deep breath in and say 'Hmmph', and the negativity leaves you.
So these sounds have their own vibrations and they mean something to our system. If someone has reservations, they do not need to do it.