Meditation JourneyAn Inner Journey Towards One's Self

Is there any possibility of damage of our internal system from awakening of the kundalini ?

"Kundalini awakening never damages you. But as far as the bad management is concerned, a person who has no authority to raise kundalini tries to do some nonsensical things, naturally there is a damage because they have no authority, divine authority, and they are doing the job. But so far there are so many Sahaja yogis all over the world, and also the Sahaja yogis have given realizations to people. It doesn’t do damage. It’s your mother, and when you were born she took up all the labor upon all herself, she took up all the pains upon herself and saw that you were not hurt. In the same way this mother, she knows everything about you, she’s the loving mother, the most loving mother, and she is not going to bother you at all. Some people do write like that, that “kundalini awakening is very difficult, it will do you damage” and all that. It is only just, just to see that people don’t get their realization: it’s just to frighten, or maybe it’s a money-oriented nonsense."
- (from Shri Mataji's discourses)

When we sit down to meditate, should we concentrate on all our chakras one by one or just on one chakra only?

Ideally you should only focus on your crown chakra during your meditation, unless you have any problem in any specific chakra as such. When your kundalini is awakened, you will feel the blockage of every chakra on your palm and on fingertips. And in case you feel some chakra very strongly, like as heat or as a tingling sensation, you can focus on that chakra for some time and take corresponding mantra or affirmation. And when it improves, you can move back to your crown chakra. Below may find some directions on same:

“If you have a liver problem, rubbing a little sugar on your Nabhi will be a good idea. Or if you have the left hand side problem of Nabhi, if you rub a little oil or ghee or something it will be a good idea. And then concentrate on that. Try to put attention onto that, especially the chakras which are not all right. You just pay attention to it and meditate on them. Pay attention to it is the main point. If you pay attention with the mantras saying, that’s how you can meditate on every chakra. And if two people can do it, it is a better idea. Is, you see, in your back, on your back.”
- (from Shri Mataji's discourses)