When you are standing on the ground there is indeed an upward force exerted on you by the ground. This force is called the "normal force". It acts perpendicular to the surface you are standing on and its magnitude is equal to the weight of the object. In other words, the ground pushes up on you with a force that is equal to the force of gravity pulling you down.

The reason this does not lift you up is because there is another force acting on you: the force of friction. Friction is a resistance to motion that occurs when two surfaces are in contact. In this case, the friction between your feet and the ground prevents you from moving upwards.

The amount of friction depends on several factors, including the materials of the surfaces in contact, the roughness of the surfaces, and the force applied. In general, rough surfaces have more friction than smooth surfaces and soft surfaces have more friction than hard surfaces.

The force of friction is always in the opposite direction of motion. In this case it acts downwards, preventing you from lifting off the ground. The greater the force of friction acting on you, the harder it will be to move upwards.