Changing value of bool at random time within limits

What I am trying to write is a piece of code that will change the value of a bool from true to false and visa versa at a random time between say 1 and 3 seconds. I've tried many methods using random. etc and attempting to set a timer that resets but it just doesn't click. I'm using c# which I'm quite new to so I'm not sure if this is a simple trick or something more complex. Any forums or videos are much appreciated anyhow.