Anthropology is the study of humans and society and when the Church is "doing theology", it is informed by anthropology. There are some theologians who have a high anthropology which is a shorthand way to describe the idea that humans and human society are very capable. Americans, in large part, hold a high anthropology. Americans believe humans can "pull themselves up." There is a multi-million industry dedicated to self-help, self-improvement and "life hacks." Even Christian churches teach that if you do things you will get rewards such as growth and joy. A high anthropology gives us the impression that through human creativity and ingenuity the world will be better.
If a high anthropology is one that puts a lot of faith and hope in the work of humanity, a low anthropology has much less faith and hope in humanity. This does not mean humans are worms and that we are worthless, rather a low anthropology takes seriously the fact that humans are capable of doing great destruction and evil. Even the most educated person can participate in evil acts, even the most loving person is capable of horrendous actions. Having a low anthropology means that one has hope and faith somewhere else.
For the most part, non-religious people have a much higher anthropology than religious people, but this is not always the case. As mentioned above, many American Christians have a very high anthropology and it is not limited to liberal or conservative expressions of the faith. As such, those with a high anthropology (including but not limited to non-religious) have no idea what to do with Ash Wednesday.
Specifically, Ash Wednesday is a day where the Church stands up to say, "give up." Not give up chocolate or social media, but give up in a more foundation sense. Give up the value of a high anthropology. Give up idea that there will always be success with hard work. Remember that none of your self-improvement will actually work. Hear that the expectations we believe are driving us to be people who "crush life" are the very expectations that are crushing our lives.