Patricia, I hear you.
When I retired I made the mistake of being lured into what we call relief teaching here in Australia.
One thing I noticed is you are not regarded as part of the staff by many schools.
The other is, despite the drop in salary you are often working as hard as hard as any full-time staff member and taking work home.
I have a friend who as been doing it for years, and I do wonder.
This year I plan to volunteer and do things that give me joy.
To be honest I don't need to fill my day in with activities. I do lots of walking, gardening and writing here on Medium.
I'm also getting my home ready to move as my husband died suddenly - another reason to re-think going back to work.