I use mine while exercising, i use it everyday cycling to work. I've taken to keeping it in a rigid sunglasses holder and have a belt fitting for that, but its not ideal although mytracks and mixzing running over bluetooth. Mytracks voice announce feature is superb.
But for navigation I need a better solution as I need to see the screen.
This might suit you I reckon http://www.amazon.co.uk/Duragadget-Waterproof-holder-mount-Mobile/dp/B003UAM2ZS
Don't know if the touch screen would work through the cover though.