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.