Looking to get back into sales

My name is David Olson and I am currently employed as a project engineer on a heavy industrial power plant. I earned a bachelor's degree May of 2010 in Industrial Technology with a Construction Management Emphasis from Bemidji State University.

During my high school days and during my college years I worked for GNC(General Nutrition Center). During that time, roughly six years, I worked as a sales associate and was often offered a management level position from the company. I could not accept it due to my school load as well as being a college athlete in the sport of football.

Since my employment from sales to construction management I have wanted to get back into sales. I don’t feel the self satisfaction after an 11-16 hour day that I did with an 8 hour day in sales. I have a personal desire to work in sales, in a career where I can succeed competitively among my peers. I am very conscientious when performing tasks that are assigned to me, and I feel that I offer the skills, determination, and self motivation to thrive in this profession. I am confident that my interpersonal communication skills and sales experience, along with positive energy and commitment to excellence, will contribute to the success of any company I am employed with.
I have applied at various online job search websites and have had nothing in response. Each of my attempts I attach a cover letter and resume. All of these attempts I have made have been for those looking for “Entry Level to Experienced” sales people. I am wondering what I am missing to get a response and would also like to ask how some of you got into this field.
Any advice is greatly appreciated!!!