"A pure thought from a pure heart is better than a mantra." -- Sri Sathya Sai Baba
When I learned Transcendental Meditation years ago, I was given a mantra, which was a Sanskrit word to chant. Today I practice Mindfulness Meditation, and if I happen to use a mantra, I can basically say whatever I want to myself that has personal meaning or significance to me at that time.
If I want to say something like "I choose happiness," I don't intend for that happiness to last only while I'm meditating. For me, the whole purpose of using a mantra is to imbibe the very word or phrase I'm chanting or repeating, and once my meditation is over, I want the mantra to keep on resonating and reverberating throughout my day.
Whatever our mantra is, even if it's a well known sound like "om," which is intended to create "spiritual transformation," the best way to continue "transforming" is to hold that sound or word within you, and call upon it whenever you desire, which doesn't mean only when you're meditating.
If you think about when you say the words "I love you" to someone -- you don't just love them only while you're saying it. You continue to love them because the feeling and meaning of those words remains in your heart. I consider that "walking your mantra," meaning that you live the words you think or chant.
Here are some ways to "walk your mantra":
1. Pick a mantra that resonates for you.
2. Use it in a meditation.
3. Say it to yourself in the morning while you're in the shower or getting dressed.
4. Hold that word or phrase within you throughout your day.
5. Say it to yourself at different times, e.g., at work, driving in your car, at an event.
6. Repeat it to yourself before you go to sleep.
If you view your mantra as a thought worthy of repeating because it holds special meaning or is sacred for you, then you will let it be an important part of your life and all that you do. If we all walked around holding a beautiful mantra in our mind, imagine what kind of "spiritual transformation" we would be creating collectively.
Now that could be a very powerful "om!"