One of my clients asked me last night why intervals. Here are 7 reasons that will make you start working out this way today! I think it also keeps things moving fast and you do not get bored so easy. I am not that person who can run on the treadmill at the same pace for 10 miles (boring). More power to you if you can. Now give me an interval workout on the treadmill and I'll do more miles and time will fly!