A word of caution
When you first start practice meditation, you will find a lot of unusual changes in your body and mental state. Be prepared for the unexpected. Remember, meditation is a cleansing process. You are throwing out the suppressions and blockages of not just one lifetime but many lifetimes; you are flooding your body with energy that it isn't used to. In some of the meditations, you will be jumping around, whirling, screaming, doing things which you haven't done in a long long time! Your system needs time to cope.
Initially, you may experience a lot of heat in the body, headaches, a tingling feeling in your fingers and toes. All this is caused by the sudden onrush on energy. Some of you may also suffer from pain, sleeplessness, even depression. These things are temporary. Continue with the meditation and they will disappear.
If you are suffering from a serious medical condition, or if a technique is persistently giving you trouble, consult your doctor or drop the technique.
But don't let these anxieties stop you from trying out any technique!
Simply go ahead and immerse yourself in meditation.
You will see that your life is transformed before your own eyes.