It is undeniable that people are very reluctant to make changes in their lives.
This sounds a bit stereotype statement. Not every man or woman is reluctant to make changes in their lives. Quite contrary, some really look forward to changing.
It is undeniable that people are very reluctant to make changes in their lives. Once we are comfortable in our everyday routine, we merely think about changing it, fearing about losing the current comfy lifestyle.
You could have said -
People generally are reluctant to accommodate changes in their lives. ... this helps you to qualify the ones who look forward to changing :D
Although people who have been doing the same job for years are able to complete the task easily, they are usually less satisfied about themselves.
It's better you opened your essay giving more hint that you are going to talk about what problems it may cause;
Resisting change may affect us negatively.