My exercise regimen has turned into a habit. I've been getting strange feelings in my muscles, as though they want to be exercised. Skipping a day makes me feel wrong. Not in a rational sense, but rather I feel on an intuitive level as though something that should have happened didn't. In other words, I've been going to the gym because my body tells me to and it feels weird not to go.

I have had this experience before (~10 years ago). However, the last time I injured myself and ended up taking enough time off for the habit to break. Hopefully it works better this time around.

This gave me the idea to do something similar with my thesis work: to form a sufficiently strong habit of working that failure to do so just feels unnatural.