Another thing i have found to work great for me is the lifeproof belt clip quickmount. I went ahead and zip tied the belt clip to my right side camelbak stap right around my shoulfer area and have already been to about 4 events and have not had it fall off ever. For $20 its great and it has a lock on the back side that keeps your phone from being able to be removed. https://www.amazon.com/Lifeproof-LifeActiv-Belt-Clip-Quickmount/dp/B00UIF2GUO/ref=sr_1_2?ie=UTF8&qid=1523474992&sr=8-2&keywords=lifeproof+belt+clip+with+quickmount
I use one of these clipped to my right shoulder strap:
https://www.amazon.com/Lifeproof-LifeActiv-Belt-Clip-Quickmount/dp/B00UIF2GUO