Many of us working adults are having too much stress because of our works. Mostly if you need to interact with a customer. Many customers are very irate that causes stress to us plus the negativity of the work environment, so let me tell you how I cope with these kinds of stressful situations. 

1. If you have a customer that shouts at you, or the one that we called "irate customers", just let them rant and say all of the things they want to say until they feel like you are really listening to them, try to feel where they are coming from and you'll understand why they are angry. in short Don't take it to personal. 
2. If you have a stressful work environment , Try to work silently don't mind them. It's much easy to work with your own, you'll see once you try. 
3. When you're about to leave at work or finish your shift, always take a deep breath and smile. 
Even though you'll gonna do the same thing the next day, atleast you survived the work today.