I love a good interval workout. I’m always looking to switch it up on the treadmill, so I put this together to vary my speed and intensity for a a 30-minute run. If you are more or less advanced with your training, you can adjust the speed accordingly. If it’s too intense, subtract .5 mph from each interval and see if that works. If you need more of a challenge, push yourself to go faster during the 6.5 intervals. This is a good workout that works for me, but test it out until you find a pace schedule that works for you. I also recommend keeping an eye on your heart rate by either using a heart rate monitor or using the sensors on the machine. Be careful that you do not exceed 85% of your max heart rate for an extended period of time. You can read more about this here.
Please note that I am not a personal trainer or a licensed fitness expert. I post workouts that work for me, and if you choose to try them, please make sure you are doing so safely. It is recommended that you consult your doctor before beginning any fitness regimen, and trust your body enough to know if you are pushing yourself safely.