That's an excellent question.
Here is what I believe!
The body is physical!
If you want your body to be in good health and work WITH you, you need to TRAIN + EAT HEALTHY.
It means that the best way to impact on your physical body is to take PHYSICAL action.
A thought won't train your muscles.
What will train your muscles is EXERCISE!
It is really that simple!
Many spiritual seekers make the mistake of believing that total health and well being will be magically granted to them through a meditation technique or that it's a mind trick you can practice.
In my experience, that's not the way it works at all.
Your ability to choose healthy food and train your body is a magical and divine gift.
This power that we have to choose our actions including what we eat and how we use our bodies is the first power we should use when wanting to be in good health.
If you are out of shape, eat unhealthy and never train, meditating on health won't change you much.
It might motivate you a bit and align your intentions.
But ultimately, what brings you health is ACTION!
TRAIN + EAT HEALTHY!
You have to do that consistently and think long term.
Makes sense, right?