Whatever it does for your physical fitness, enduring the tedium of two hours on a treadmill must improve your mental toughness!
Last year I was a volunteer participant in an experiment at the National Centre for Sport and Exercise Medicine (conveniently located just the other side of the cricket field from my office in Loughborough). It involved two sessions of 45 minutes at moderate intensity on the treadmill. Even with the experimenter chatting to me to relieve the boredom, I was continually watching the timer and thinking about how long I had left.