In my view you need not have a spiritual intent, nor do I pass any judgment on how it is done other than to sit quietly, focus on breathing or anything that you think may help you. A mantra, for example. Wish I could recommend a definitive book. Have a number of books that speak to it or include sections about it. What served me best was to just go ahead and meditate. Keep reading about it.
Believe it requires a leap of faith. I fervently believe in its healing powers that accrue with time, patience, and persistence. Do not pretend to be any authority.