I'd argue that any "invention" that falls into the "wouldn't it be neat if..." domain is obvious, and under existing law should be rejected outright as the basis for a patent.
In this particular instance, was you sister "skilled in the art" of developing treadmills or software? If not, and it's obvious her her, chances are it's blindingly obvious to someone who is skilled in those arts, and presumably works in those fields.
In this particular instance, was you sister "skilled in the art" of developing treadmills or software? If not, and it's obvious her her, chances are it's blindingly obvious to someone who is skilled in those arts, and presumably works in those fields.