The correct lower body position is to rest your knees lightly on the fuel tank after choosing a comfortable riding position, and to keep your knees "close" to the tank at all times. It also allows you to keep a good sense of control as the real time dynamics of the bike are communicated to you through your legs.
(Tip: We have found that the misconceptions of the novice driver's posture are either over-tensioned or relaxed. Over-tensioning can be seen in sitting back with an excessively stiff back, stiffening the shoulders and forcing the neck into a fatigued position. (Another misconception is that excessive slackness is reflected in the fact that the rider's legs are not close to the sides of the tank, resulting in a reduction in the rider's ability to control the bike.
We have all experienced that when we first started driving a motorbike, we would clutch the handlebars with both hands because we were nervous. Because of this, we often have sore hands and arms after only half an hour of riding, and the ride is unusually stiff and difficult to control. This is what we always mean by "don't grip the handlebars too hard".
It is also important to remember that holding the handlebars is not just about controlling the direction, but also about controlling the throttle and brake and clutch handles. When you grip the handlebars with brute force, can you still turn your wrist freely to control the throttle? Can your fingers still control the brake and clutch with the right amount of force? (Tip: The reason for the repeated emphasis on holding the handlebars easily is to be able to manipulate them more flexibly. The bike is not stable because you have a firm grip on the handlebars, but rather because you are limiting the natural back-and-forth nature of the handlebars to correct direction.)
Here we should also emphasise how to operate the brakes and clutch. The brakes and clutch require a relatively moderate grip on mainstream crossbikes nowadays, so we can usually operate them easily with the "two-finger method" or "three-finger method" (Two fingers: middle index finger, three fingers: middle to little finger). In some motocross competitions, the brake grip can even be easily operated with one finger.