/diy/ - Do It Yourself

I am planning on making a shed in my backyard to set up a small personal gym. It's mainly going to be used for heavy lifting (deadlifts, clean and jerk, etc) so I will be dropping weights and need a solid foundation.
Here's the caveat though; I don't want to pour a concrete foundation as there is a good chance I will have to move the shed around overtime.
Does anyone have ideas as to what I could do? I thought maybe to lay down some concrete garden stones.