your limits should be like a traffic light
Although not an original idea of mine (I saw someone saying this expression before and I think it was on LinkedIn) the method of respecting yourself in the manner of a traffic light is an exercise in self respect.
The psychology behind it is very simple. If you tread lightly with people trespassing your limits, it turns out you don't really have limits. If you keep suppressing yourself in order to fit others (being their lives, their schedules or whatever), you'll be putting other people on top of you. Even though I have values that allow me to be empathetic, I should not go along with something I don't agree with and could even pose some harm to me or my family in the short to long term.
Here's an example.
Why don't you go on and drive through the red light? It's simple. The consequence is clear as day. You could hit your car and have to pay your insurance firm to get it running again. You trespass in a higher speed and you might get hurt. You cross it at 90km/h (that would be around 55mph for you, my dearly beloved American citizen) and there's a good chance you'll kill someone or even get yourself killed. The consequence is very clear. That's why no one in their sane minds drive through the intersection when the red light is on.
So now bringing it to a tangible behavior; does anyone keep getting late in your meetings whenever you set the date and time very clearly? Instead of waiting, just stand up and leave (or drop out of the meeting room). Later someone will text you "hey I joined in just 8 min late and I couldn't find you there". You'll then later reply "hey, our schedule time was 2. want to try again tomorrow? i'm available at 3." In that small exercise, that little fella that under prioritized the time you made available to them will be 5 min early the next time.
I found out that this really works in various aspects of life. Some more immature people might mistake you for intolerant while some others that can understand the values of someone else's time will get the message right on the spot.
This should also be applied to other aspects of your life. You shouldn't tolerate these behaviors and you should establish consequences to those who violate these terms. Just like a traffic light. Yet, don't be harsh on this topic or you'll find very quickly that this tends to upset the majority of people.