Using the public speaking example, the person could first create an audience in their mind and imagine speaking to them while performing the relaxation. If the person cannot create an image in their mind then a picture of a audience could suffice. If there are specific worries related to the speech, like forgetting what to say, that can be worked into the scene. Once comfortable in that situation, the next step could be making the speech in front of one familiar person, then a small familiar group, gradually leading up to the actual speech.
A couple of important tips to remember. For every specific worry there needs to be a counter thought or solution. If the worry is forgetting then a solution could be making small cue cards so the person can easily access a way to stimulate their memory. If answering questions is a worry, then help the person come up with specific answers to anticipated questions prior to the speech. If the anxiety is related to a lack of knowledge or skills then those need to be taught first. The other aspect to keep in mind is that desensitization is not a method for encouraging people to perform activities they find unpleasant. This is only to be used when the person wants to do an activity but experiences sensations of anxiety/duress when trying to do so. It is important to respect people's preferences and gain consent prior to starting any exposure procedure.
Steven C. Altabet, Ph.D.