If you fear getting airsick, you might want to consider taking ginger capsules before going for a spin. At the beginning of my PPL training, when my stomach was not accustomed to the feeling of having left solid ground, they helped me quite a lot.
As for the spinning itself, just relax. I was pretty awed by the idea of being in a spinning airplane myself until I did some spin and UA training in a Citabria (which is by and large a less aerobatic Decathlon with flaps). Given enough altitude and C of G within limits, there is nothing nerve-wracking about it, and the g forces in the pullout are no big deal either (as stated by DAR and BackPacker, a) they need not even attain 4g and b) they only last for a moment).
Whatever your personal experience, an important point IMHO is that intentional spin training at altitude has nothing to do with an inadvertent stall/spin at low altitude (which is why I am somewhat skeptical concerning the safety gain from spin training and rather side with those who believe that eliminating spin training from the PPL syllabus in favor of stall awareness is justified with regard to stall/spin accident prevention).