I can't deny the sense of calm I've felt after praying, for example.
This is a good example.
If you learn about 'mindful meditation' (ie, google or visit your local library if you like books, and find credible sources, read, and make a logical conclusion), you will find that it accomplishes the same thing. In fact, it is recommended by medical practitioners as a valid form of relaxation for people with MI and cancer.
There is a strong argument to be made for 'prayer as meditation' ... ie, when praying, you enter a stage of dissociation that is akin to meditating, and the mind empties, the heart rate slows, and voila - calm.
Prayer = a religious form of meditation. *
.
* It should be noted that some religions validate and include meditation as part of their practice. xx tal