Looking for a good spa/hotel max. 3 hours from Brussels

Hi all - i'm hoping for some suggestions... work has been incredibly stressful and i need a quick (weekend) getaway. I'm hoping to go somewhere w/in 2 - 3 hours from Brussels... hotel/spa...would love to be on a lake or near mountains. someplace to relax and unwind for 2 days. Note, I would be traveling by myself, so preferably nothing too romantic or "honeymoon" focused. thanks!