Why Some People Are Always Late

— -- New York City's Mayor Bill de Blasio is notorious for constantly being late, but the politician's chronic tardiness made headlines this week when he was so late to a memorial service for 265 people who died in a plane crash that they held the moment of silence without him.

The mayor later apologized and blamed a "rough night" and fog that slowed his Police Department boat that took him to Queens for the anniversary of a 2001 plane crash, but he left people irked with his persistent lateness.

De Blasio's inability to be on time mirrors many other people with lower profiles than the mayor of the country's largest city.

Time management expert Julie Morgenstern told ABC News there are two main types of perpetrators: people who are routinely 10 or 15 minutes late, and people whose lateness varies.

If people are always late by the same amount of time, the problem might be psychological, said Morgenstern, who is not a doctor but has extensive experience studying time management.

"If you think about it, they're precise," she said. "They always arrive exactly 10 minutes late. If you're always late by the same amount of time, you have to realize you're arriving at the exact time you want to. There is some sort of fear or discomfort of down time. There's a lot of anxiety about sitting around and doing nothing."

The fix? Set a goal to be early -- instead of just on time -- and give yourself an incentive. If you're 10 minutes early to dinner, that time can be spent browsing Instagram or shopping online on your smartphone, for example.

The other group of latecomers has a bigger problem with managing their time, said Morgenstern, author of "Time Management from the Inside Out."

"It typically means you're really bad at estimating how long things take," she said. "You think, maybe I'll do this quick thing or take this call, and you end up running over."

This type of person doesn't necessarily mean to be late. They just think a quick stop by the post office won't make them late to lunch, when in reality it's out of the way and there could be a long line, for example.

"I've had clients tell me, 'Even when I'm on time getting somewhere, I find myself adding something and then I'm not on time anymore,'" she said.

Morgenstern said those people need to pay attention to how long things really take, and also learn how to say no.

"If the phone rings when you're walking out the door, just keep going and don't stop," she said.