Originally Posted by Oso Polar

Yes, and one more thing that no one mentioned so far - many riders at first always ride as a dead weight, as a sack of potatoes mounted and glued on top of the saddle, always strictly fully seated, including the moments while going over quite rough terrain (pavement cracks, potholes etc.). Lift up yourself at such moments a bit (or more), so that road bumps instead of transmitting directly from the saddle to the butt will be soaked and amortized by leg joints. Avoiding these kicks in the butt over the rough road makes a huge difference for the stress on the rider's body as well as for the stress on the bike itself. Roughly, if you remain always glued to the saddle than if a bike goes over an obstacle than it lifts whole weight of a bike + rider, if you are already lifted though then only bike weight needs to lift and "springs" (legs) compress.