Losing Weight On A Treadmill

I have been trying to lose weight for the past year.  I did alright at first and dropped ten pounds right away.  After that I have only been able to lose five more pounds in six month.  It does not seem to matter how much I cut back on calories, the weight seems there to stay.  So I looked at cheap treadmills and found one in my price range.  It is being delivered tomorrow and  hope that the extra exercise along with cutting calories will help me drop the other twenty pounds that I want to lose before my high school reunion next year.