I Had A Submandibular Sialoadenectomy Surgery On My Left Side.

I had a Submandibular sialoadenectomy surgery on my left side. Prior to my surgery I had a strong drive and motivation for exercise. I cant seem to get it back and have a serious struggle to even exercise longer that a week. My body no longer seems to have the energy either. It has been 2 years now since my procedure and have never been this out of shape. What could be happening?