For example, when giving a presentation you will likely be consciously thinking about the structure of your speech, and maybe reminding yourself to maintain eye contact with your audience.
Beneath the surface, however, your unconscious mind might be managing nervousness, and these feelings could be influencing your body language, like fidgeting or a shaky voice, without your direct, conscious awareness.
Such anxieties might stem from past experiences or deep-seated beliefs about your abilities, which you are not consciously considering at the moment.