But you should understand how you get the reward or blessings of the Puja and its prasad. A Puja or a prayer grows from your heart. Mantras are the words of your Kundalini. But if Puja is not performed from the heart or if Kundalini is not associated with the recitation of Mantras then that Puja becomes a ritual.
If you become thoughtless in Puja, know that your heart is also involved in it. Collect the Puja material and offer it sincerely. There should be no formality or bindings in the offerings. It is correct to wash hands, but is your heart washed?”
H.H. Shri Mataji Nirmala Devi, Old Letter in Marathi – Meaning of Puja.