It is critical to be on time for every appointment that you have made, or to let the others involved in the meeting know that you will be late as soon as you realize it. This is common decency, yes, but it has a greater importance.

There is someone else on the other side of your agreement to start the meeting at a certain time. They have stopped what they are working on to attend the meeting on time. If you do not show up on time, they cannot start the meeting, but they also cannot leave, because they don’t know if you’ll show up the next minute or not.

Each minute that they are away from their work is a minute of productivity that you have stolen from them. This is not only disrespectful but also counterproductive. If they are a customer, investor, or recruit, they will not engage with your company. If they report to you, they will keep quiet but resent you. There is no winning scenario when you waste someone’s time.

But life happens. A previous call or meeting may run late. Traffic doesn’t always cooperate. Even with careful planning, it’s not possible to be on time for every meeting. The good news is that you don’t need to be.

It is only critical to let the other members of the meeting know that you will be late as soon as you realize that you will be. And you must come to this realization (and let the other attendees know) before the meeting starts, through whatever channel will get to them the fastest. Ideally, you’d let them know about the delay before they have to break away from whatever they are doing before the meeting.

In addition to being on time, you must also be present. Being present means that you are composed, prepared, and focused on the subject matter. It can take a few minutes to “get present”—prepare for the meeting, research the topic and the attendees, go to the bathroom between back-to-back meetings, get a drink or a snack, and so on.

Therefore, I recommend that you plan to arrive to an outside meeting fifteen minutes before it is scheduled to begin. For a meeting in your office, wrap up your current project or previous meeting five to ten minutes prior to the scheduled time for the next meeting.

To make this easy, I recommend scheduling 25 and 50 minute meetings only (Google Calendar even has an automated setting for this). This will give you 5 minutes for each half-hour and 10 minutes for each hour to maintain yourself.

When in the meeting, I often see leaders making the mistake of constantly checking their messages. They cannot get away from being “on,” if even for a second. This is not only disrespectful, but it defeats the purpose of the meeting, which is collaboration with the attendees present. It sends a message that the meeting’s content is relatively unimportant. Furthermore, it also breeds a bad habit for the entire company—one that will be hard, if not impossible, to break down the line.

During every meeting, leave your phone in your pocket or face-down. Sticking with the strategies of Getting things done will help you to focus on your meetings and make the most out of your assembled—and expensive—talent. And if the meeting is not efficient, then make it so (see Running meetings).