I think it is *much* harder to push a stroller than just walking alone. However, I also think that maybe the road, or the type of stroller might make a difference. I think the jogger strollers (you know, the 3 wheel types) are designed to make it easier.
For me, I have a double stroller, so I usually have 2 kids in it LOL Lemme tell you, it does NOT get easier when the older sister tries to climb in to make it 3!!!
My stroller has also been practically mangled by rolling over soccer fields that have loads of gopher holes.