For most people, a prerequisite feeling for tranquility, is contentment.
And trust me, no pacifist is "content" with the current state of the world. "Worry-free" is literally in the first sentence on the wikipedia page of the word, and I don't think anyone can be that, except temporarily and/or by being inebriated.
The only way I know to be tranquil, is to ignore the world, and willfully focus only on the good things in my immediate surroundings, in my life specifically.
Essentially, to get there I have to take a break from caring about most things. I don't like doing that. I want to improve things, and to do that I have to care about things to begin with.