You already know what you should be doing. The problem is one sentence you keep telling yourself, repeated so often it stopped sounding like an opinion and started sounding like a fact. "I get lazy near the finish." "This never lasts more than a month for me." That sentence decides things on your behalf, and no habit tracker ever reaches it.
This book works on that layer. Eight short chapters on why motivation cannot carry you, how your self image decides before a habit ever gets a chance, why your brain pulls you back to the old way exactly when things start going well, and what you do on the day you don't manage it. The ideas rest on Festinger, Bandura, Beck and Gollwitzer, and where the research is contested the book says so.
Every chapter ends with an exercise that takes five to fifteen minutes and is written to be done, not read. The last pages give you a plan for your first seven days and a table you can print and tick off.
For anyone who has already tried and stopped. It reads in one evening. It works over months.