How can I do crunches properly? After doing ten or so crunches, my body refuses to lift my back, without ever getting to feel the burning in my ab muscles.

To give some context, I go running several times a week and I'm very fit. For years I've been doing crunches the wrong way for years, and I've only yesterday learned about how to do it correctly, but after 10 or so repetitions, I can't lift anything other than my neck, and my abs are not even hurting, as though doing crunches excercises everything in my body except my abs. There is definitely something I'm doing wrong, please help me.

Thanks for all the replies everyone. I will be ditching crunches and trying out other workouts for the abs.