"I can't" versus "I don't. Which one is worse?

"I can't" versus "I don't. Which one is worse?

I was listening to the Art of Manliness podcast because I train women all day and need to do things to boost my testosterone. And the guest that day was Jeff Haden, author of the book The Motivation Myth: How High Achievers Really Set Themselves Up To Win. There were...