I like to think of it as “we didn’t fall out of the trees all that long ago, in evolutionary terms!”
The one that kind of worked, at least for a while, was external reward. I set point for each task or habit I want to achieve, and the longer the streak goes the more point I earn. Point can be used as currency for rewards. I monitored my motivation against the tasks to iterate on the point distribution design. It worked great for six months in which I regularly slept and waked up early, did spanish vocabulary anki sessions, and no phone during remote work (“no phone for two hours” task,) etc., until I used all my point for a M2 IPad Pro which was the ultimate reward I set for myself from the very start.