If the soil is dry and has nice loose texture you can build a screen that will allow the soil to fall through but separate the rocks out.
To build a soil screen, simply make a square out of 2x4's and staple hardware cloth to it. Each time you go out to the garden just shovel a few shovelfuls of soil onto the screen and shake it until the soil falls through.
If you have a small garden you can get the entire thing done pretty quickly, if you have a big garden you can just section it off and do a little at a time. Even if it takes you a decade, eventually you'll have gotten all those rocks out.
Gardening is mostly an issue of your enthusiasm holding up until you get used to the work.