Earlier in the year, I worked out how to stop being 10 minutes late everywhere.

The reason why I’m constantly behind schedule turned out to be counterintuitive. I was too organized for my own good, trying to effectively spend every last second of spare time cramming in as many to-do items as possible. Instead of spending the final five minutes before leaving the house idly flicking through a magazine, I was trying to sew buttons back onto coats and quickly cleaning out my freezer drawer. In my effort to be productive, I wound up being less time-efficient.

And so I vowed to slow down and accept the concept of free time, instead of turning every spare moment into a race to tick off chores. I’m happy to report that it’s working well so far. But I’ve also realized that while a lot of people feel embarrassed about running late, there’s an under-appreciated positive trait that most unpunctual folk share: People who are consistently late are incredibly optimistic.

We’re the type who thinks the play won’t actually start until 7.08, or that we definitely have time to stop for a coffee and make the train. We believe we can walk or drive faster than GoogleMaps tells us—and while that may be true, we also overestimate just how fast our legs can spin in their hip sockets.

We cannot transcend the rules of physics, no matter how invincible we feel on a day when all the traffic lights glow green.

Many times I have felt like I managed to find a rip in the space-time continuum, allowing me to overcome insurmountable time barriers. Aha! I would cry when I managed to sweat my way through an 18-minute walk in 14 minutes. Einstein was wrong—the speed of light isn’t a constant! But we are only human, and we cannot transcend the rules of physics, no matter how invincible we feel on a day when all the traffic lights glow green.

As a result, we build unrealistic expectations of what we can achieve in a given amount of time. This applies not only to the time spent getting between point A and point B, but also to our perception of how much we can accomplish over the course of a day.

For example, one day I experienced the ideal commute: I power-walked to the station, had a train pull into the platform as I arrived, hopped on a second train waiting at my transfer, and then sauntered into work after only 25 minutes. After I had this one-hit wonder of good fortune, I held onto the hope that 25 minutes was my new standard.

But this is the optimist’s delusion. The reality is that some days my commute takes 25 minutes; other days, I swipe my ticket to realize there’s no money on my Metro card, get to the platform as the first train is pulling away, hit maintenance delays on the second, and roll into work after a 45-minute journey.

You’re not late because you’re disrespectful of others’ time: It’s the byproduct of believing that you’re superhuman.

The same goes for work itself. Do you write a daily to-do list that you never seem to get through? Or beat yourself up when you only strike out half of what you wanted to achieve? This doesn’t mean you’re being unproductive—it means you’re being far too optimistic about what you can achieve in 24 hours. No amount of schedule reorganizing will create more than 1,400 minutes in a day, so you need to learn to account for the chance that your half-hour meeting will bleed into 45 minutes, a timely crisis will need to be averted, and a whole slew of unexpected tasks will land on your plate by noon.

So if you have a guilt complex about being late, take heart: you’re not innately selfish or disrespectful of others’ time. You’ve just made the mistake of believing that everything will always work out.

In order to counter this habit, we should not aim to be less optimistic. (After all, we need as much of that in the world as we can muster right now.) Instead, we should just focus on recognizing that we’re not superhuman. Ideally, this means we’ll spend less time beating ourselves up about what we’re not doing and focusing that newfound space on actually achieving something else.

For example, create a buffer time on top of your travel plans. Greg McKeown, the author of one of my slow-down bibles Essentialism: The Disciplined Pursuit of Less, suggests adding 50% to your normal travel time to account for delays. This might seem like a bit much, but when you plan for things to go awry, you’ll be able to stay calm when you hit some literal roadblocks.

Another important step is to assess how you’re really spending your time. If you feel like you’re never making it through your to-do list, take a moment to map out how much time you spend on admin tasks during the day (email can take up to 25% of your day, for example) and factor that in to your list-making. Or try some totally different ways of subdividing your time at work, such as using a Bullet Journal or the Pomodoro Technique.

Our optimism shouldn’t excuse us from our tardy lifestyles. But we can use it to be nicer to ourselves. You cannot predict the unexpected, but you can prepare for it.