My gf enjoys being spanked with my hand from time to time while we are having sex, usually while I am taking her from behind. She also enjoys her hair pulled and being choked, so she does enjoy a certain amount of pain and domination. Well, yesterday while I was getting ready for work, I was putting on my belt and started to pretend to spank her with my belt. I thought nothing of it, but later that night at work (we work together) she caually makes the comment to me that she was thinking about that encounter earlier with my belt. So I guess I am asking for advice to how I would encorporate this into our sex life without coming on too strong or turning her off by hurting her too much. For she does enjoy pain and domination, but does not like being belittled or completely dominated.