Read a book. (You can read free books online and through apps like Libby and Project Gutenberg)

Visit your local library.

Sew. Or learn to sew. You don't even have to be good at it to enjoy it.

Go for a walk.

Listen to music.

Draw.

Start a journal, write a story or write some poetry.

Call or video chat an old friend.

Watch your favorite movie.

Play a game.

Cook something.

Organize your place.

Clean.

Go to a free community event. (You can check out Facebook Events for events near you)

Take a free online class. (Websites like Khan Academy are great for this)

Do yoga.

Play chess. Or learn how! Meditate.

Learn magic. (Or anything else that may interest you, Youtube is free.)

Web Surf. (StumbleUpon is a great website to find cool stuff online.)

Go to a local museum.

Listen to a new podcast.

Gather and donate old clothing items.