I think an important question is: what are your wife's fetishes (everyone has them). What turns her on? My partner is not really into bdsm, but she is very GGG and as long as she's not actually being hurt (e.g. light bondage, light spanking) she'll play along. I think part of it is that it's a big turn-on for me and she's turned on by my excitiement.

If you beat your wife without her consent it's not play anymore.