Showofhands,
I think it is best to listen to teachers who have come from industry rather than those who haven't.
To me, the physical delivery of lessons, the planning, paperwork and duties is not hard if you have come from a corporate background. It's not a patch on it, tbh.
What is difficult is the relationships you have with other people - children (obviously), parents and teachers. Behaviour from all three groups can be quite shocking.
You probably had a pretty good experience at school - top sets, surrounded by compliant classmates. As a teacher, you have to deal with pupils you were aware of, but never had to share airspace with, at your own school. And behaviour gets worse across the board year on year. You probably were friends with equally nice kids, so did not experience poor parenting.
As for colleagues, teachers are a breed apart. I think this was the #1 culture shock for me. In my corporate life, I did what it took to make my project succeed. As a project manager, the buck stopped with me. I did all the decision making, and my superiors sagely nodded their agreement and offered some dollops of wisdom. The work was done from the bottom up, and the hierarchy was there to support and empower.
In teaching, it's the opposite. People have TLR points to do certain tasks. It can be frowned upon to do tasks without being paid (in money or time). It's easy to step on the toes of those who have a point or two. There are a lot of prima donnas in schools.
If you are the type of person who sees a job that needs doing, and does it, you might be frustrated with your colleagues in school who prefer to whinge that it is someone else's job. I have been (and found it difficult) but I have mellowed with age and experience.
I do love teaching and the wider contributions I make to the school, but it is a bit of a process to get where you feel comfortable.
BTW, when I worked in industry, I worked in the same company as my DH doing a similar job. He is still there 18 years on. I can safely say that my job is much, much less demanding than his (although he is paid 3x what I earn and has fewer holidays).