Run-walk intervals, very good really (or at any rate strenuous and warm!); I felt initial self-reproach at having to lower the 'run' speed from 6.5 to 6.0, but then remembered that the last time I was doing intervals it was just a ladder of 1-2-3 and back down again, so no surprise that 6.5 felt a bit fast. If I am patient, I will be a lot faster in a couple of months...
10 mins. warmup jog, then 10 x (3 mins. run @6.0mph, 2 mins. walk @3.2mph)
60 mins. total