For me, lateness is often a kind of weird procrastination. I decide to leave for a thing at the last possible moment, which is often significantly later than that. But punctuality is extremely valuable and valued in our society. There are huge benefits to being on time, everything from better relationships to higher income. It shows a capability for self control that some people have innately and others, frankly, have to hack their way toward.
I'm working on getting myself there, but don't forget to also forgive yourself when you slip up and show up a few minutes late in the same way you would forgive someone else.