Anal being painful every time.

No matter how horny, mentally prepared, or lube is used, it always hurts. My boyfriend absolutely loves it and the way he talks to me when we're about to do it makes it worth it but it is just too painful. I end up crying and shaking and he feels like shit. I just want it to not hurt. Are there any numbing lube that anyone recommends? It makes me happy to please him but obviously I don't want to be feeling like that. We had one good experience with it and it was great but it keeps hurting now (we only do it like every 6 months).