I'm writing up some productivity/metrics tools for myself to help monitor my focus throughout the day. Recently, I've noticed that I tend to get off track more than usual and feel the need to get up and go for walks/drinks/etc and I'm concerned that I'm "wasting" too much time.

Since I always lock my computer when I go anywhere, and I unlock it as soon as I return (even if I'm just reading at my desk, etc), I was wondering how I can determine, in code, how long the machine is locked.

I'm writing this in C# if that helps, but I'm open to other ideas.

I like the windows service idea (and have accepted it) for simplicity and cleanliness, but unfortunately I don't think it will work for me in this particular case. I wanted to run this on my workstation at work rather than home (or in addition to home, I suppose), but it's locked down pretty hard courtesy of the DoD. That's part of the reason I'm rolling my own, actually.

I'll write it up anyway and see if it works. Thanks everyone!