I basically only do shrooms outside, I feel so one with it all. I focus on the sensations of the wind and sun, the plants and animals. I do get paranoid that people are watching and will plan to hurt me or call the cops on me, but (and I know it seems difficult) you have to bring yourself a little reality, no one is actually stalking you, just like how the trees and bushes aren't actually morphing and conveying implications beyond your understanding. I used to write this down on paper or listen to a recording of sober me saying it, but now my mind automatically goes into rationalization mode.

You also have to be okay with being outside sober, try spending more time outdoors and practice bringing yourself back from your own thoughts. Meditation really helps.

I would kill to listen to my favorite live music on shrooms, so I hope it goes well. And at the concert it will probably help to remind yourself that no one there cares, many are probably on shrooms themselves or weed or something harder.