Don't worry, lots and lots of people feel this way once in a while. Just remind yourself that you can stop at any time, and be exactly as you were beforehand.

I myself tend to scare myself with such thoughts, especially during WILD.

Whenever I these feelings get too disconcerting, I like to get out of bed, and try to put distance from these thoughts. Maybe listen to some music, or drink something soothing. Once you have calmed down, you will be able to try again without much trouble.

If all else fails, try adapting a mantra. Anything to keep a sense of reason.

Avoid thinking of the journey, think of the destination! This will also help you enter dream-state if you happen to be WILD'ing.

Good luck, and don't worry, you are not alone!