"I am always mentally photographing everything as practice."
Minor White
You can continue to develop your compositional awareness sans camera, iphone, or for that matter, any equipment other than your vision. On my way to the clinic each morning, I have various routes, which I alter, to provide seasonal opportunities to see and envision new work-a newly emerging wildflower, first frost, the gogebic range in various stages of snow cover, etc. No worry of exposure or technical variables, which focal length lens, but a sole focus on composition and existing light. Excellent practice. There is one downside. Without being able to capture your vision in that moment, you can be almost guaranteed, that if and when you return, the myriad of variables (lighting, time of day, weather, your own emotional state) will not remain the same.