Exercise and fear

I have no excuse for not exercising.  I was told and read about the benefits of exercise.  I ate a lot of bad foods, so why exercise?  What good would exercise do if I continue to eat bad foods, especially if I am losing weight?  That is a good point.  I need and would like to, just start.  Just do it.  I wonder what I am really afraid of.  I wonder if this is the case of looking inside myself to see why I have whatever fear I may have.  It is time that I start, even if it is for just 5 minutes.