It's practically impossible...
It's not. I have a couple of systems, too, which were rebootet last time several years ago. When the system is stable and auto updates are off, why should a system not run for years?
systems? My PC at home is always running for a few months straight and I usually turn it off only to upgrade HW but that's Linux. I honestly never heard of Windows running for years. Congrats if you've managed to do that.