I had a book a while ago, maybe 10-15yrs ago, written by an ex army/SAS type person about learning to trust your instincts. It was really good and had some great advice. The only bit I can remember though is when he leaves a club or bar, he pauses for a few minutes to see if he picks up in any danger. It was all to do with how your brain processes so much information and you're only aware of a tiny percentage, so if you give yourself time to stop and think, you can notice signs that your brain picks up that you were previously unaware of.
Annoyingly I lent the book to a friend who I then lost contact with, but I'd really like to read it again.
I'm sure it had something like 6th or 7th sense in the title, and his name began with a J, possibly Josh.
This is very vague so thanks for reading and thank you even more if you manage to work out the book from my crap description!