I have absurdly high, unrealistic expectations and perfectionist standards. I force myself to lower my expectations (for myself, for other people, and for situations) so that they are reasonable and realistic, and remind myself not to be upset if things don't go the way I anticipate.
I'm gentle with myself, and with other people. I remind myself everyone makes mistakes, or not everything has to be done a certain way. I leave wriggle room so if I (or they) fail, another route can be taken -- and forgive myself (or other people) and learn from my shortcomings, instead of being harsh and critical or upset.
I ignore social media and go for walks, or read, or paint, etc. or just soak in a bath listening to nice music. Or I will cuddle my pet. These quiet moments give me inner rest.
I used to do none of these, and I was very angry, disappointed, bitter, and stressed almost all of the time. I had to learn to let go, be reasonable, be amiable, and understand that I do not always have (or need) full control. It took a long time as it was a learning process which went contrary to my natural personality, but now I am much happier. A boon to it is that now I have many friends, a nice side-effect I hadn't expected.