Good afternoon N, your essay is very good. In general you have proved your stand point and provided good examples. I just wanna add some comments on grammars as follow:
It is generally believed that people often not only change jobs but also do not identify themself with only a job throughout their working life. From my viewpoint, I absolutely agree with this statement.
The first reason worth mentioning is that people who change jobs in order to (to do what? Lack of verb) further their career. In addition to this, in a fast-changing world, workers need to be flexible to gain experience or develop a range of skills. As an example, statistic shows the median years a person stays in one job is 4.1 years(2008). In other words, an average on average, a person will have to ( have to sounds like forcing or sth) have 7-10 different jobs in their life time. Consequently, (consequently is used for the result of the action or sth, it is not suitable here, maybe Usually?)people often look for another opportunity with higher salary or more appropriate from another company. By saying this I mean, it is completely acceptedable that nothing is wrong with people just trying to keep up with modern society. (This last sentence does not match with your first statement of this paragraph, You first said changing job can improve people career but you just concluded this paragraph with a sentence saying that changing job is nothing wrong? It seems not convincing enough to me, maybe you can add a concluding sentence for this paragraph like: Indeed, changing job is....blah blah. )
Secondly and more importantly, there are good reasons why some people feel the need to make vital changes their work from time to time. First of all, changing jobs is interesting and challenging, this can be opportunity to learn and grow up. A new job, for instance, might present challenges that motivate the person to adapt, obtain new knowlegde, and learn different skills. Furthermore, as well as possible making life more fun and exciting, new experiences can be good for their physical and mental health.
By way of conclusion, I once again reaffirm my position that nowadays it is difficult and impossible for many people to stay in the same job during their working lives.