I suffer from OCD (Obsessive Compulsive Disorder), which is a very irritating condition. My father, James and my cousin (his niece), Vicky, also have it. It affects how you do certain things, for example, if the table is laid a particular way, this is how you always want it and you just won't sit at a table laid any other way. But it also brings up a lot of intrusive thoughts, and this is the symptom I suffer from the most, which make it impossible to merely put one foot in front of the other without conjuring up images that only someone with the mind of a sewer would get any merit out of seeing.
Thankfully, it does respond well to medication. They are looking into this now for me, but I won't go into this as it's confidential. If you suffer from OCD, it's always good to remember that these are just thoughts. No one other than you can see them. You are what you do, not what you think. I have also found that breathing exercises prove effective against a variety of mental health conditions. At the risk of sounding cliché, they are genuinely helpful. You can do them anywhere, and often no one knows you're doing them.
Let me know what you do to help with OCD, I'd be interested to give it a go.