I do not think there is a very easy job: every job has its pros and cons. It can sometimes be easy and sometimes difficult. But if someone likes what he does, he finds it easy.
It really depends on the subject that you are teaching and how engaging your students are. Remembering that you will always have to be on top of your game.
No job is easy but lecturing job have it's own challenges. Teaching in country with poor educational infrastructure and high poverty rate of citizens is very challenges. Passion and love for the job are the strength.
It is not an easy job. But it looks easy for those people who are passionate about it. For example, a good student or topper of the class doesn't reflect the character of becoming a good teacher or lecturer in future. To be a good lecturer, one must have the ability to be connected with the students by reading their minds and their capabilities.
It would depend largely on whether you are an instructor teaching 200 level or lower level courses or a professor dealing with 300+ level classes including graduate classes. The former would require minimum extra preparation once you have taught the course once or twice. The latter is comparatively more difficult and would require some preparation to challenge the students.
Academic work in higher institutions like universities involve lectureship and research. In general teaching is a gift. It comes naturally. People are gifted differently, hence a doctor may not be interested in medicine and an engineer does not want to be a teacher. Imagine sending a lawyer to the farm, he will grumble all day.
Academic work is exciting to one so gifted because such picks a problem or human need, researches about it, informs the world about his findings in publications and disseminates the information to the class and at conferences, meanwhile takes comments and continues.
There is never a dull moment for such a person. That job is the most exciting in the world. People who think it is stressful are not gifted for it. Its like grinding iron to iron like a machine without lubricating oil.
Academic work It is not easy for a teacher to learn all about the topic that is connected with knowledge and of the latest developments and be ready for any question is delivered by students.
For information the person must be full-time full-time
Initially very challenging and difficult also ,face intelligent students with their doubts, after experience things becomes bit simpler still it requires hard work,sincerity and devotion