I too used to 'cut corners' at practice in school and walk during runs in gym
I was a rebel !
I also stayed away from the treadmill for 2 years of my 80 a month gym fee.
Then one of my coworkers finally lost that last 10 lbs on the treadmill. We were both cardio 'queens' and I knew that we did the same levels at the other machines so I relented and one day walked over and got on the thing.
Well, lucky for me I had cardio conditioning but I realized that with that conditioning that jogging -NOT running was a cinch ! Before too long I began to jog faster-never have I run
But let me tell ya, the pounds FELL OFF. It was like a sudden miracle ! So get the courage up and go for a trot ! Or do what the others [many of them almost too skinny] at the gym do and walk at an incline. The ability to change speed and incline make the treadmill the perfect metabolic challenge machine ! If you have access to one, it may be the dream machine for you that it was for me.
Good luck, I know YOU CAN DO IT