What does rebounding feel like for beginners?

I've seen a few people say that they can barely do 5 mins, but why?

I'm trying to figure out if I'm doing it wrong, or if it's supposed to feel like I'm walking up an extremely huge incline. I just did my first session ever, and could barely make it 2 mins because the back of my calves were screaming at me.

Am I doing it wrong, or is that supposed to be the experience because my legs aren't used to it?