Exposed surface area = 1.5 m² when we are lying flat on our back..
Thrust = pressure * area
= 10⁵ Pa * 1.5 m²
= 150,000 Newtons.
This is a very high amount of force spread over our body. we are actually accustomed to this force.
When we want to lift a force of (weight of) 10 kg ie., 100 Newtons, we feel a lot difficulty.