For examples if you wanted to rename /long-distance-running-page/ to /marathons-are-easy-page/
Install the Redirection plugin (if you don't already have it).
Go to the Pages page.
Click "Quick Edit" on the page you want to change eg. Long Distance Running Pages
Where it says "Slug" change the URL there eg. marathons-are-easy-page
Click "Update" to save it.
Then go to Tools -> Redirection.
Click Add New.
In "Source URL" type in the old URL eg. /long-distance-running-page/
In "Target URL" type in the new URL eg. /marathons-are-easy-page/
Click "Add Redirect"