Before I could be rehabilitated though, I had to realize 2 things:

1) There are occasionally things that come up that are totally unforseen and out of our control. But that was almost never why I was late. Getting places on time is almost always completely within my control, should I choose to exercise said control.

Which led me to needing to realize that

2) Being chronically late is another way of exerting control over situations. It is at best a total disregard for other people (my time is so much more important!) and at worst an overtly hostile act. The motivation depends on the situation (late for gathering with friends, late for family functions, late to work in the morning) but it's useful to figure out what the motivation is. I had to start saying out loud some of the internal justifications I gave myself to realize just how bad they sounded. I imagined saying them to the person's face who I was making wait for me. Especially my husband. That motivated me to stop it.