What will happen if you sit too long?

Answer 1

You mean, REALLY long, like if you sit for like, 3 weeks or so?

You get bedsores (or pressure ulcers) on your butt.

They are basically large wounds, and very difficult to heal.

It happens when patients in hospitals lie on beds for too long, though nurses will normally come to turn them over and make them walk or sit for at least a short period of time to remove the pressure from their backs (if possible).