I don't think you can lay all the blame on age for your overwhlem with librarying and teachng. It's a very difficult profession that, in my experience, became worse with a wave of budget cuts beginning in 2008 or so. Then they lay on the tech (tablets) and then, Covid, which maybe came after for you. I found teaching exhausting and extremely impressed with people who managed it for 20+ years. I did it for five, starting in my mid-40s.