We don't feel or are not crushed by the atmospheric pressure because, the pressure inside our bodies is equal to the atmospheric pressure and cancels the pressure from outside. 

On exerting force, an object that is not rigid may change its shape.

e.g. flour can be kneaded in any shape.

An object exists in a state of rest or in a state of motion. 

When a force is applied on a body at rest, it can start moving. e.g. a stationary football is kicked.

When a force is applied on a body that is in motion, it can also bring it to rest. e.g brakes in a vehicle. 

Similarly, a force can change the direction of a moving body as well as the speed of moving body. e.g. a cricket ball hit with a bat. 

When air is pumped into a tube, the pressure inside the tube becomes more than the atmospheric pressure and exerts outward pressure, thus inflating the tube. 

Force is an external influence (push or pull) on a body that tends to either change the state of a body or its shape.

Actions like pushing, pulling, picking, hitting, lifting, running and bending are some of the examples of force.