Everyone is replaceable, so disavow yourself of the notion that you’re not. But if you knew that upper levels of management at your job considered you imminently replaceable, how many weekends would you work? How many extra hours would you work? How many vacation days would you not take?
Life’s too short to think about your job as something more than a means to an end. Don’t build castles in the sky. Your likely source of career progress is your next job, not this one. That’s the way it works nowadays. So, do a good job, but take all of your vacation days. Don’t let them overwork you, or else it becomes an expectation. Your time is more valuable than you can imagine. You’re in control. They need you; you don’t need them.