I used to be really bad about time/punctuality. Since doing a startup where the tides were relevant, and missing a rendezvous by 10 minutes could mean a 12h wait (not just for me, but for a lot of other people), I made a serious effort to be punctual -- the big change being focusing in advance on "we must leave no later than X to be there on time" vs. "we need to be there at X+Y" is 90% of it.
