Aflame

I recently read a book by E.M Bounds and its just fantastic the way he describes the little details Christians should have. In one chapter he talked about having the desire for God,

The desire for God that stays far behind the devil and the world at the beginning of the day will never catch up.
It is the overwhelming desire which stirs and breaks all self-indulgent chains that does so.

Holiness energizing the soul - the whole man aflame with love, with desire for more faith, more prayer, more zeal, more consecration - that is the secret of power.

I don't mean to say that having an overwhelming desire for anything must bring an overpowering sense of change or a show of physical appearances; such as the way we act or speak. But I do know that if we are passionate about something, we do tend to show a degree of desire or passion no matter how little that degree is.
The more you talk about a matter close to your heart, the more effort or passion or desire will be placed in it, and it will definitely not be hidden.