Cheesy video, but a good overview of the Cinque Terre :)
There are tons of beautiful hiking trails connecting the different towns! Most are moderate hikes, but they all have views and require walking up / down steep stairs at some point on the trail. Worth the effort though, we promise :)
You can rent umbrellas / seating for the day and chill on the beach if working up a sweat isn't really your thing. Note the beaches in Italy are stone, not sand so water / beach sandals are reccomended.
The Burnaco Vineyard (Wedding Venue) has a great wine tasting you can reserve. Perfect way to end the day if you went for a hike and want to chill ;)