For mantras, as I'm taught in Pranic Healing, besides radiating specific vibrations which allows specific parts of aura to respond, certain energies radiate out of aura, they are also heard by specific energy beings.
When speaking with sincerity, there is the Gayatri Mantra for healing and protection that works... Just repeat over and over again till one is better.
Lakshmi Mantra is a version of Gayatri Mantra geared even better for prosperity.