It really just depends on what you are reading, Descartes isn’t really intended to be used as a practical philosophy, it is used rather for Ontology, Science, and Theology. So it is too theoretical to apply it to your life. But if you really tried I’m sure you could some how, but I wouldn’t know haha… Other philosophies however, are immediately accessible, like as you brought up one of the stoics. Philosophers like Aristotle, Plato, Socrates, Nietzsche, Kant have an applicability to them as well. Really what most philosophers have tried to do is change how we think, many of them have succeeded, if you look at the philosophers of history, it is very easy to see the circle of influence they have after their philosophies integrate into society. Some philosophies are immediate nuggets of wisdom, others perhaps are more passive, but can change whole cultures.