Of course my issues can be a bit different from yours but what I do is to lock the world out from my head and do the things that feels engaging and fulfilling to me. It will be different things for different people of course, but I find that having inspirational projects to work on over time so I can do a little each day, or when I feel like it, very helpful. I have been unfortunate to have started projects that became too much for me and caused me stress themselves. I had to stop and start over again. Now I have found great help in my forest project with this camp area I make just for fun. Being outdoors in a place where I don`t have to worry about people, where I can experience nature and let my own imagination and ideas have room and quietness to operate. It sets me free somehow. Gives me the space and freedom and the relaxed state of mind I can`t have when I am around people. Although I often pretend to have company and talk out loud when I am out there. 
Then I still feel a need to be inspired by other people and then I turn to books, audio books, movies, internet for interesting sites, Ted-talks, art (I really appreciate the Display your artwork-thread here on WP!) etc. I also enjoy Wikipedia and I like to read about historical persons like writers, scientists, philosophers, inventors etc as well as ancient cultures and rulers. And I have this fascination and appreciation for timelines and animated illustrations.
I don`t have to go out and meet people very often in my everyday life but still I feel like it is to much sometimes. Exercising seems to make me feel a bit stronger mentally as well. I have health issues so I will never be super fit, but I can do fairly well with the capacity I have.
If I feel very very low I sometimes need to go to bed and almost pretend it is evening so I can do the stuff I do when I go to bed. Like making a hot water bottle, put on my jazz channel on the radio and read or put on an audio book. Ad some lavender oil because the smell has become a familiar smell of home to me. If I fall asleep I take it as a sign that I needed it.
I also find peace by lighting candles in the room I am in. Candle light has a calming effect on me as well as interacting with my animals.
Humor must also be mentioned. If something makes me laugh I feel better. So I have some favorite comedians and comedy shows I can turn to if I feel in need of a good laugh.
Something good to eat also comforts me and I try to stick to not so unhealthy food as I have struggled with eating disorders in my past and know that I can`t challenge myself too much. It isn`t smart of me to use food for comfort too much. But I control it well today. My favorite meal when I am feeling distressed and low are casseroles.
At the moment I am in this mode that I wish I didn`t have to see anyone. It is unrealistic and it will pass and I`ll feel better eventually, I know. It is just the way it is. When I was up in the forest earlier to day, fixing on my camp, and were digging mud out of the stream that will run so beautifully through a part of the camp area, I didn`t think about much else than the mud and the water and if the stream would run faster and cleaner now, and it was such a relief. To focus on something as concrete, uncomplicated and real as that.
I do feel like I am fighting bad emotions/worries, thoughts and memories every day as my experiences seems to get stuck in my head and body, but the things I have mentioned are helping me. Not that I become completely freed from my problems but it helps me keep myself up and going and gives my days some quality too. These things might be completely without any calming, comforting effect to someone else since people are different with different issues. It is interesting though to hear how other people find peace of mind and motivation. 