It is up to us to decide how we wish to live our lives to make life worth living to us. It is this self-directedness that makes life meaningful. Russell Blackford and Udo Schüklenk, 50 Great Myths About Atheism (Wiley Blackwell, 2013), 34.
There are many things wrong with that claim. To begin with, it simply begs the question. Whether that's sufficient to make life meaningful is the very issue in dispute.
But here's another problem. The claim is so elitist. It presumes that people have freedom of opportunity. But what about a slave-state like North Korea? Apart from the ruling class, do individual North Koreans get to decide how they wish to live their lives to make life worth living to them? We could easily multiple analogous examples.
And even apart from totalitarian regimes, many humans just don't have a great menu of options to choose from. Their circumstances force them to eke out a grinding subsistence existence.
Yet atheists typically deny the afterlife. So this is your one and only shot at life. If we grant how the authors frame the necessary conditions of a meaningful life, hundreds of millions of humans, maybe billions, never get to enjoy a meaningful life. And there won't be any compensations for anyone in the world to come, since there is no world to come. Therefore, the "myth" that "Atheism Robs Life of Meaning and Purpose" is often true even by their own lights.