People choose to use hypnosis to gain greater control and choice in their lives. If they fear total loss of control it's best to help them understand that I can not make them do things against their will. I can't even hypnotize them if they are not cooperative and the best way to achieve cooperation is to have their intentions and wishes in mind. If I were to begin to suggest something away from their goal it would create resistance and the client can and would emerge themselves from trance.
Clients come to help make changes that are usually outside of their will or understanding. Hypnosis increases and enhances your self awareness and provide an amazing level of clarity and fulfillment in their lives. It is absolutely safe and you will never lose control.