It would be a little easier and more effective if your husband would like to assist, but you can do the following by yourself. Your husband could first guide you in relaxing every muscle in your body; asking you to tense a muscle group, then relax it. (This will help you become more skilled at discerning tension of your body.) Using a calm, reassuring voice, he can talk you through this process, perhaps starting with your forehead, then your jaw, hands, stomach, buttocks, and so on. Each time you exhale, sink deeper into relaxation. Then, when you are fully relaxed, and your heavy eyelids have closed, your husband can talk you through imagining various sexual things on your list, starting with the very mild and proceeding slowly toward things you find a little more challenging. He must instantly stop his description when you use a prearranged signal to indicate that the thought is making you just a little tense. At such times, revert to full relaxation, picturing yourself doing something you find soothing, like imagining yourself curled up in front of an open fire or soaking up the sun on a deserted beach on a glorious day.
When, over several sessions, you consistently feel relaxed about thinking of something sexual that would previously have disturbed you, try making your thoughts more vivid by imagining every detail. When you feel relaxed about this, try recalling the most beautiful sexual feelings you have known even if at this stage such feelings are very weak and then imagine yourself feeling even more pleasure than that, as you daydream about doing that new thing with your husband. Ensure, of course. that you continue to feel beautifully relaxed.