There are three things that are important for a film. Number one is story, number two is story, number three is story. Good actors can save a bad script and make it bearable, but good actors can't make a bad script good - they can just make it bearable.
As an actor, you want to do the best job possible, and you want the best scripts possible because it makes life more interesting.
Being an actor is often very tedious, which is why it helps hugely if your fellow cast members are also good friends.
I have never really believed that acting is very difficult. I think some people have a skill and are able to act, and if you have that natural gift, it's not difficult.