Shell,
Not to speak for Tresses, but I do know that many individuals who are sensitives or have special abilities or gifts find that they do not work so much on demand but rather when want to.
For many years I've always thought that I have no special gifts and I have admired those that are sensitive. Well just recently I've come to realize that I am a sensitive as well but just in a different manner. I'm more of an empath. I've often wondered why I can tell what's going to happen but only when it comes to the actions of people. I've always wondered why I could tell what people are feeling before they tell me. I've always known I'm a "fixer". Just never quite related it all together.
But in my case, I can't force it to happen nor can I "over think" it. When I try to do it, it doesn't work. If I'm related to the person or it involves me, it doesn't happen. Mostly because the brain overrides the instinct.