I love teaching. It's hard work but really rewarding.
Your workload will vary greatly depending on your stage/year group/subject as well as by school and the demands the SMT put on you in terms of paperwork.
I've been at the same school for 20 years nearly and the workload has varied over time.
Currently, I'm the least stressed I've been I think. Mostly because I've been in my year group for a few years and know my planning/resources/material well and can be very efficient when planning for activities inc differentiation. We also have a very low demand placed on us for official planning or paperwork and very few observations. That may always change q soon with a new headteacher.
We also (Wales) have had only a small change in the curriculum recently and are due a massive overhaul of it following the Donaldson report, so that's due to change too.
Being on form all the time and not being able to be off your game for whatever reason is very stressful. Staff at our school have had family bereavements, supported family through distressing conditions and have had their own medical problems, yet still we are expected to be on the ball. It's a necessary part of the job, but one that makes it difficult on some days.
I love how the job is always changing. I've not moved schools, but have moved year groups. And even when you stay in the same year group, every class is different and you change your topics etc from time to time so things are always kept fresh.
One difficult thing is the fact that you are judged on your performance in a field where you can't ever do something perfectly. Any lesson, however well it went, could always be 'better' in some observers eyes. And the behaviour of your pupils, which you can also be judged on, is something you can influence, but that ultimately you are not in full control of.
One memorable feedback I had from someone was that there was nothing wrong with my lesson. That the material, the expectations and the behaviour management were all spot on. "But you just didn't sparkle. I know you can do better than that." Told to me by a visiting observer who didn't know me at all.