A mantra is a Sanskrit syllable, word or verse that when repeated,creates sonic vibrations that encourage spiritual awakening.  Any sound that speaks to your heart, will suffice.  They say that whatever you choose, make it melodious and meaningful, since your enjoyment of the word's sound and connection to it's meaning contribute to a mantra's power.  Repeat it silently or audibly as you take a walk, wash the dishes or sit quietly.  Is repeating your own mantra the way to gain a dose of serenity?