Rotate an element without ending point, is it possible?

I want to rotate a circle and to repeat the action for ever but without ending point, is it possible to make it as a fluid action?

Here's how...

Thanks for your help, my action was already looping, but in fact I’ve found that the problem was that my rotation curve wasn’t linear but was animated with an acceleration curve. It’s why my action looks like there was a ending and a beginning point.