When using your mattress for the first time, unroll it, open the valve for 24 hours on a flat surface, then inflate it and leave it for 24 hours, valve closed, under pressure. Then you can store it away again. While trekking, take out and unroll your mattress as soon as you set up camp, valve open to facilitate pre-inflation. A self-inflating mattress inflates to about 60 to 70% on its own. You will need to blow up the rest yourself, so you can adjust the pressure to your desired comfort level.