Exactly right. If you don't have a power tool, then a long wrench (or pipe extension) will give you the leverage.

I use a flywheel stop like this, and pop the wrench handle with a hammer:



But unfamilia's method is a better way. Two long bars, one to hold the engine, the other on the bolt. You can pull the bars towards towards each other, and it won't rock the engine (at least not too much).

Something like this?