I'm not trying to bore anyone, but here goes ...
I've mentioned that I walk/run races - half marathons, 10Ks, 5Ks. My preferred course is a park trail, for the (usually) beauty and for the extra challenge of hills. Some of the trails are terraced into steep hillsides and very narrow. Then throw in exposed tree roots, smooth rocks that are slippery when wet, ruts from rain run-off and, sometimes, mud. Yes, I am weird. Anyway, it's tough enough keeping good footing without slipping or turning an ankle and occasionally letting faster runners pass. I do not want some one on those trails passing me or me passing them who is not fully aware and capable of perceiving reality accurately!
I also do some work with weights for the sake of some balance in my fitness. Though I currently do not belong to a gym, I have in the past. There is significant skill in lifting safely - oneself and others nearby. As above, I do not want some one on a machine or using free weights who is not fully aware and capable of perceiving reality accurately!
Safety should never be compromised because some one likes how it feels when exercising while in a chemically altered state of consciousness.