Yes, you'll encounter stress in a social worker career. You'll have days where you're working against a deadline, trying to get services lined up so you can resolve a client's crisis. You might have worked tirelessly to help another client get back on track, only to see them crash and burn yet again. Finally, you might feel a tad frustrated because legal constraints or other factors don't allow you to help a client to the best of your ability.
You might also have a hefty workload, which makes you think about taking work home instead of hitting the gym after work. Here's the simple solution to that one: hit the gym. You'll help ease your stress and generate some beneficial endorphins, which will help put the day in perspective.