Lateness is one of those habits that makes you less desirable in certain circles. Having managed staff over the years, I have filled out many reference forms when they have gone on to new employment. It never ceases to amaze me that out of all the questions that another employer could ask, the punctuality question makes the list of the miniscule question set.
As bad as lateness is, there is something even worse, and that is not showing up at all. Lateness can be quite embarrassing and there is a temptation to just not show face to avoid those feelings. Commitment to show up in spite of the apprehension of the undesired consequences of being late is still commendable.
If you have a lateness problem but still show up no matter what, try focussing on the positives of your commitment. As you keep focussing on those positives, it gives you more of an emotional credit to be able to tackle the main problem of lateness. If you are ever late again, remind yourself of this.