We are all influenced by others. Science is even finding that our brains fire in the same response as someone we are watching. The mirror neurons.
If you believe you are vulnerable to psychic interference it's not wise to go into meditative practises without knowing how to protect yourself. People have found themselves more troubled as a result.
To protect yourself fortunately you don't need to go into deep meditation. The imagination is strong enough. Imagine yourself surrounded by light. (White being universal is good) Imagine it getting stronger as you think about it. Imagine it protecting you.
I suggest the Paraliminal Self-Esteem Supercharger to to build your confidence.
AlexK
