I grant that without action, results on any desire will vary. 'The Secret' is not a secret and it is not new. Check out the Planetary Commission, for example.
This said, I have been amazed sometimes how a 'bad' mood is switched almost instantaneously by fully feeling gratitude (and I mean to the depths of your toes) for a specific memory in the past or a specific person or thing in the present. Snap of the fingers, as they say. There are naysayers but don't believe everything you read or hear till you try it for yourself. After all, one person's 'woohoo' can be another person's 'wtf'.
This can apply to situations, too, not just mental states. Usually, there is a time lapse between the visualization/'feeling the feeling' and its manifestation but sometimes, Universe gives you a smack on the bottom with a 'See this?' and gives you a taste of the manifestation within minutes/hours.
This just goes to show how thought is action (one thing biblical that is on point: thought is deed). The physical action is repetition. Good for solidifying our feelings and making us view ourselves as productive but, essentially, repetition. True story.