I am a social worker, so you can imagine the high stress and fast paced environment. I make sure to give myself at least a 10 minute break every couple of hours to relax and refocus. I also keep my work separate from my home life, otherwise you'll always feel like you're on the clock. For me that means unplugging when I'm at home, not checking my work phone for texts and calls, not checking my e-mails, and only allowing myself to check my schedule once before I go to bed (I travel a lot so I need to know where I'm supposed to be in the morning).
I also try to eat right and exercise regularly - which can be a struggle. However, when I'm on my health kicks I always feel so much happier and relaxed! What you put in is what you get out.
Sleep is also hugely important to reducing stress. An adult needs, minimally 7-8 hours of sleep on average. Sleep helps balance our emotions and improves our memory and focus.
I also have to remind myself regularly that it's okay if I'm not always "perfect" and that I can ask my co-workers and supervisor for support when I'm overburdened with work or dealing with a difficult (and often emotional) case. Social support not only makes us feel better, it allows others to know what our needs are and therefore makes them more capable of helping us.
Lastly, as cheesy as this may sound, when I catch myself becoming overwhelmed and emotionally overloaded I meditate. For me it's not so much a spiritual thing as it is a way to slow down, find my calm, and refocus my energy into a more positive direction. Simple breathing exercises and a peaceful environment do wonders for the mind.