A lil' personal activity I find helpful is changing my environment. When it gets hard to write, I just grab my notebook and head out to a park and write about my environment. It's pretty simple but the output product is always lacklustre, however, more often than not I get lost in thought and some fresh ideas and vitality in this regard end up coming to me. My most recent venture produced two paragraphs of a first person perception of a bee that was buzzing around me.

Good luck!