He already spends much of his time giving optimistic speeches to the American public (or at least, to his supporters). One would think he’d welcome the opportunity to do more of this.
The presidency already demands a level of engagement that seems beyond him, and yet he’s still president. One can only assume that he delegates the boring stuff to his underlings, or (as discussed in the “Who is really calling the shots on all Trump’s executive orders?” thread) that he just endorses whatever unsolicited plans his cronies and lobbyists manage to pitch to him. I don’t see how he’d need to change any of this behaviour if there were a war.