When the elements force you to run inside, logging miles on the treadmill can get dull fast. Once a week, mix it up with a “treadhill” workout.
Warm up by jogging for 10 to 15 minutes, then adjust the treadmill incline anywhere from 6 to 12 percent. Slowly increase your speed until running feels quite difficult. Maintain this for 30 seconds. Then gradually bring down the incline until you are slow jogging/walking at the same pace for 30 seconds. Then slowly increase the incline again until you are running with difficulty for 30 seconds. Repeat.
From week to week increase the number of reps as well as the speed.