Validating Steam Files

I’ve been pretty tolerant of this for a while, but now it’s starting to get on my nerves. When I try to start up gmod, I get a screen telling me that steam is validating files. After the files finish validating, the game works fine, but it’s really annoying to sit through that every time I start up my computer and try to go straight to gmod. I’ve tried defragmenting the files, but that didn’t help. What else can I do?