Thanks for all of the great advice I received earlier. Day 3 of the cup and so far and mostly so great! However, I was at the gym today on an elliptical (one of these: http://www.bodyconcept.com/family/1586/display.html ) and as I was working out, I began to feel the stem of my cup as it slid down. I left mid-way through my workout to adjust it and push it in higher manually. I thought perhaps it had slid out when I used the bathroom before my workout. But then a few minutes into my workout it slid down again! I think I spent most of the workout keeping my vaginal muscles tight to some degree, to make sure it didn't slide out. I doubt that would have happened anyways, but just in case.
Is this common? Is there anything I can do besides ignoring it or removing it before I work out?