An older Medium post by Mike Monteiro and still a goodie:
Why are you letting other people put things on your calendar? The time displayed on your calendar belongs to you, not to them. “I’m adding a meeting” should really be “I’m subtracting an hour from your life.”
I vividly remember the confusion I felt when I was told, “Just add an appointment to someone’s calendar. We all do it here.” This was on Day One or Day Two of my new job. My manager had thoughtfully provided a list of people that I should meet. “How should I initially approach them?” I asked. “Just add yourself to their calendar,” he said. I was horrified. How presumptuous! What a way to make a first impression. “Hi! You don’t know me. And this feels crazy. But here’s my calendar invite!” I think I’d rather show up at their cube singing Call Me Maybe!