I used to watch a show from the states about severely overweight people, with a doctor called Dr. No trying to help them lose weight (I forget the name).

Most of the people that actually lost weight ended up going to therapy first. Without working on the underlying issues, weight loss was hopeless. Once they did do therapy, the weight loss became possible, even easy.

I think productivity is a similar sort of goal. There are no hacks, no tricks, no methods. Humans that are healthy, safe, and have meaning in their life are naturally motivated.

So are you healthy? Are you safe? Do you have something that gives you meaning? If not, then work on those issues, and motivation will come to you naturally.

You would really need to be more specific about the context - it really sounds like you're talking about how to be a more productive person yourself - but this raises a lot of questions about what you in particular struggle with in terms of "productivity".

Reasons you aren't "productive" could vary from being delusional / mislead about what reasonable expectations are for productivity to struggling with energy because your diet is imbalanced, inconsistent, or because you aren't sleeping enough or with enough regularity in your schedule.

If you were actually interested in the "science of productivity" that isn't a question for an individual, but is mostly looking at workflows, in which case I would direct you to scientific management and Taylorism: https://en.wikipedia.org/wiki/Scientific_management

Individuals aren't expected to be exceptional for a good workflow to be efficient - it actually is better for individuals to just be consistent and fit a particular rate of work that has been pre-determined.

It might be that you're getting influenced by a toxic culture that sets unrealistic standards? Or maybe you're struggling with depression and framing it as a "productivity" issue when it's actually an issue with motivation due to psychological or clinical issues.

Sounds like you want psychology books.

I'll cite the greatest scientific book on productivity here in full: "Just raise your lazy ass from the sofa and start working, you good for nothing piece of procrastinating shit!"