Work/Life balance. It's definitely something I learned the hard way my first year as a manager. I tried to work 60+ hour, 7 day weeks back to back and the result was me being less happy, more stressed, and less productive than if I would have just taken a day off. I definitely let this job grind me down when I first started.
It takes you a while to reap the fruits of your labor. You will work hard for weeks or longer before you feel a paycheck. That can be stressful at times, but for me the big payday a that come in during the second half of summer have been enough that I was able to take a full two months off from any work to focus on school and still have some left to lease and partially furnish a new apartment.