You must know what your values and beliefs are. Because knowing these things help you identify what kind of workplace culture you are willing to put up with.
Say you value spending time with your family. Working under a boss who keeps on working overtime and at the same time wants you to adapt the habit will eventually undermine your values. You may be able to tolerate it in the first few weeks. But if it becomes a habit, then you’ll end up feeling miserable not only at work but also with a strained relationship with your family.
Suppose you are working under a company whose culture is to tamper with documents from time to time, but you value honesty. In that case, it’s time to leave the company.
When your values and beliefs do not match that of a company or a boss, you will evolve from a hopeful and hardworking employee to an unhappy and underperforming one.
Working under a workplace culture you disagree with will only make you worse.