"where's the evidence that willpower is trainable as promised in the intro?" In the second half of the article (linked at the bottom of the first half), they d

"where's the evidence that willpower is trainable as promised in the intro?" In the second half of the article (linked at the bottom of the first half), they describe having people exert willpower in some small area over the course of a long study, and found that by the end of the study, they also ate better, exercised more, and reduced tobacco, alcohol, and caffeine consumption. This suggests that exercising willpower is effective for building it. Without knowing more details, I can't tell you how solid that science is. But it does suggest an experiment you can do yourself: consciously exercise willpower in some small area, while tracking various habits that don't directly relate to that area. See if your willpower improves over time.