How can I give the character realistic force?

I’m new to UE and game developing in general. I’ve started a “test project” using the Third Person Example (with blueprints).

I’ve added some cubes (StaticMeshActor) and I’ve made them movable. They fall to the ground when I put them in the air so this part of the physics seems to work correctly.
The problem comes when I bump or try to push them with the player character. It’s like it has too much force. The cubes are huge and have a mass of thousands of kg, but the character is still able to move them and even send them flying without effort.
What am I doing wrong?

(Sorry for my clumsy english, I’m trying to improve it but it’s not my language.)