One of our SunnyHillsMeditation.com members mentioned he has a "wandering mind" when it comes to using a mantra.
Seems to me we all have wandering minds.
I think the idea of a mantra is to practice it a few minutes at a time, until we start building up more focus.
The easiest way to focus, is to sit in easy pose, and meditate with a straight spine, eyes closed, and focusing at the brow point.
Also, tying the mantra to the breath, of course.
It's more challenging (= more difficult) to breathe with a mantra when we are moving around during the day.
Although, going on a walk, or going for a run, can put us in sort of a meditative trance that helps us focus on our breath and on our mantra.
My challenge is to try to breathe 4 times/minute (when I'm restful) with a mantra going, trying to do it all day long, or even for an hour, or even for 5 minutes or so.
If I'm more active, walking or working with body movement, then 8x/min is more reasonable.
The yogis say if we can breathe 4x/min all the time, then we will have achieved enlightenment.
Or vice versa, if we have achieved enlightenment, then we will be able to breathe 4x/min all day long.
I hope this helps.
At least it's something to think about.
p.s. The idea behind having a 1x/week distribution schedule for each mantra couplet of my personal 28-part meditation, is for You to try using the mantra couplet of the week, whenever You can during that week.
If You can do it even for 5-minutes during 4 or 5 days of any given week, with each given mantra couplet during each matching week, then You will have achieved something really great, and You may notice how impactful it can be on Your mood and/or Your self-image.
That's why I titled the 28-Part Meditation: "This Is Who I'm Becoming Now."
Sat Nam & Bless You!
President, Bizbuild.com, Inc.