If you're receiving a reposition alert from the Spire app, this indicates that Spire isn't able to confidently sense your breathing in its current position. To fix this, try adjusting Spire or changing your posture.
If you're seeing this message when wearing Spire on your waistline, your pants may be too loose or low to detect inhales and exhales. If you're wearing Spire on your bra, try moving Spire to the side or center of your bra.
In order to sense the expansion and contraction of your thoracic cavity as you breathe, Spire needs to have a snug fit against your body (though not necessarily touching your skin).