Few years ago I decided to challenge my memory by learning few characters of the Divine Comedy by earth.

I don't know how much my memory got better but as a side benefit I got a great meditation technique for when I feel overwhelmed with my thoughts, or cannot sleep. I just have to recite one character silently and all the brain resources that would be wasted to feed my stress will go into the activities of recalling, visualising and enjoying the poem. It's the greatest stress relief method I found.