Where do you usually do your tempo runs? I'm debating right now between the track and the roads (don't need to worry about cars, and the trails are too wet/muddy to run on, plus no trails that go on for a long time that are good for tempos). I guess for roads I could run out one way for 30-35 minutes and then try to run back faster/turn that into a tempo effort on the way back and measure it afterward?