Sharing a room teaches you that solitude isn’t a door you lock. It’s something you carry with headphones and a notebook.

Solitude is a state rather than a place. When a door is not available you learn to build the same quiet out of portable things, headphones, a notebook, a seat turned away from the room. That turns out to be worth having, because shared rooms do not end when you move out. People who always had their own door sometimes never learn it.

Put a small kit together and keep it where you can reach it. Use it for twenty minutes somewhere you normally would not bother, a crowded kitchen, a bus, the back of a classroom. Notice that the quiet holds even with people talking nearby.