What to study in mechanical engineering?

Mechanical engineering is a discipline of engineering that applies the principles of engineering, physics and materials science for analysis, design, manufacturing, and maintenance of mechanical systems. It is the branch of engineering that involves the production and usage of heat and mechanical power for the design, production, and operation of machines and tools. It is one of the oldest and broadest engineering disciplines; as per Wikipedia

So, tell me what is the actual learning or practise you will, you wish to take out of your Mechanical Engineering degree?