My Trail Pro is self-inflating, though for extra expansion (or "loft", I guess) I'll put a few breaths into it. For this pad, that's OK, can't say for yours, but here's a link to the owner's manual: http://media.cascadedesigns.com/pdf/...rochure_EN.pdf
I know some of the Big Agnes pads use a bag that comes with for inflation, though I doubt it would be compatible with a Thermarest.