If you are considering the value of the activities and your deliverables within your process, be that an agile process or not, you are starting to tend towards lean. How far you go towards lean depends on how much introspection you do and how much you act on the results.
Tending towards lean should aim to remove as much waste and deliver the most value as feasible. How lean you become would be driven by an understanding of the value chain of your organisation.
In short, you can be agile and lean, but consider how much value you get from what ever you understand from each of those terms.
I am not an expert in understanding in lean, but the above captures the essence of what I understand at present (at a very abstract level).
Here are some discussions I found about this topic: