Since I have memory I've always been a really anxious and impatient person, I like when things get done the right way, that's the main reason why I do almost everything myself instead of asking for help, the past few years has become a huge problem. When something goes wrong I feel frustrated and I can't function right so everything that I do turns out bad or I simply can't concentrate, the past months I've been trying simple things that may help me relax.
I like taking three steps depending on how bad I am, the first one and my favourite is taking deep breaths, I like to close my eyes on focus on my breathing, it's a great way of dissapearing from the world for just a moment.
The second one is music, I like listening to my favourite songs on repeat, but you can also found classical music, mostly depends on your personal preferences.
Finally if nothing has worked, I like to go out for a walk, leave the place where I'm feeling frustrated and go outside, to watch how everything is right, it's also a great exercise. A little bit of sun and outside world never hurt anybody.
But I think my biggest advice is to just don't let little things get to you, don't let people know what is bothering you and if something is really getting to you try to relax and let go before someone notice it, some people just want to hurt you by doing that...