Words are power. They generate emotions in others, but in myself also. To think positively doesn't mean that everything is beautiful and well. To think positively means changing my choice of words, putting myself into a happy mood, motivating myself.
"Walking your talk"
Even our ancestors used freedom songs. "We are strong and brave" instead of "We mustn't despair" sounds much better, doesn't it? A sad picture, such a disheartened pile of human. But how powerful is the idea of the picture from strong and brave freedom warriors.
Positive speech creates positive pictures. This releases pleasant emotions and triggers the associated feelings in us. Negative talking feels like reproaches without a target specification, as self-righteous criticism, and generates frustration, displeasure or resistance (freezing, flight or fighting behavior as a reaction). It is more edifying to find out what the other person would prefer.
Manipulation
Speaking positively without an positive inner attitude in conversation, in order to reach a certain result only, creates a more pleasent feeling to the other person than criticism does, but often will been looked through and will been perceived as manipulation. Speaking positively should be more than just targeted conducting of conversation.
Creation
For me, "Spirit Talk" means to appropriate the positive way of speaking as my own, to live it and to think it, to feel empathetic with the other person und be compliant with what I express in edifying choice of words.