lmemsm

Check out the online libraries with public domain books. Your local library may offer online books as well.
http://www.distasis.com/cpp/pbtc.htm#pb11

ACM is offering free access to their wonderful and comprehensive digital library until June 30, 2020. This is a great resource for all things programming and computer related:
https://dl.acm.org/

archive.org has set up the National Emergency Library for people to borrow books in electronic format on a wide variety of subjects:
https://archive.org/details/nationalemergencylibrary

If you're having trouble reading, you can listen to books with collections like Librivox and Free Classic Audio Books.
https://librivox.org/
https://freeclassicaudiobooks.com/

You can also listen to public domain radio plays. Check out archive.org or sites that specialize in pd radio plays.
http://www.oldradioworld.com/

Try out some public domain sheet music. Sing and play songs or try some Karaoke at home.
http://www.distasis.com/recipes/music.htm
http://www.distasis.com/recipes/pdmuse.htm

If you're watching TV, turn on the closed captioning so you get some reading practice as well.

There are some great Open Source educational computer games. dnb is a psychological research activity that helps improve memory. Tuxmath can help keep math skills sharp.
https://lmemsm.dreamwidth.org/8013.html

Try some online tours using Google Cardboard, Google Expeditions or other online resources. Many museums provide an online tour at their web sites.
https://www.commonsense.org/education/top-picks/virtual-field-trip-apps-and-websites

You can do bird watching from your own backyard or window. Identify some of the birds in your area and see how many you can find.
https://en.wikipedia.org/wiki/List_of_birds
https://davesgarden.com/guides/birdfiles/

Try baking.
http://www.distasis.com/recipes/

Keep a journal. Some writing resources are listed at:
http://www.distasis.com/write/

Gardening can be done in a yard or on your porch. You can garden from pots if you don't have any ground. Vegetables can be added to your salad or meal. Herbs can add flavor or be medicinal. Some flowers are edible and can add cheer to a meal.
https://davesgarden.com/community/

Try out some hobbies. If you program or want to learn, several Open Source projects need volunteers. Look into ham radio.

Use your arts and crafts skills to recycle household items. You can also try out projects like origami.

Help out a charity. You can help feed people and learn and play games at the same time. Help out via the freerice.com site.
https://freerice.com/categories/english-vocabulary

Exercise:
https://www.youtube.com/watch?v=HqfGRx8k_zA

E-mail Pen Pals.

Meditation is a great activity and it can help you calm down, feel better and cope with not enough sleep. There are many types of meditation from visual and guided to breathing to mantra to music and walking. Biofeedback equipment is useful for some if you're have trouble getting started or concentrating. If one form of meditation doesn't work for you, try another. There are so many techniques, you're sure to find some that suit you.