Assuming you've been blessed with a reasonably decent tolerance for the sun, bugs and/or salty sea breezes, the Lowcountry offers a wealth of outdoor activities for your post-Heritage needs. Sure, it's Sunday, but like Mom told you, go outside and play; it's far too pretty out to be sitting inside watching TV.
BEACHES
This being an island and all, they're not terribly tough to find: just pick a direction and start walking, and before long you should run into one.