overeducated and underutilized

Hi, I feel that I am overeducated and underutilized. Two years ago I quit my highly stressful job where I made decent money and worked 70 hrs/week. I also had a glorified senior manager title but did not manage any people. I pursued my masters largely because I loved to study and improve myself.  I no longer want to work 70hrs a week and would be happy with 1/2 of my former salary and be an individual contributor.  Hiding my masters is an equivalent of lying on my resume, but I feel that it hinders my opportunities. How do I convey that on my resume or even a cover letter (not every posting allows the cover letter part, and recruiters advise against the Objective section)?