You’re not willing or don’t know how to ruthlessly edit.
Many executives I work with who tried hard to write their own resumes told me they spent many hours laboring over what to include and what to cut. They found it extremely painful to leave out pieces of their career history for the sake of brevity — everything was important and critical to include!
They fail to understand that a resume is not a comprehensive career history. It’s a career marketing document that needs to say just enough to capture the attention of decision makers and compel them to contact you.
Understand that these people are overloaded and have very little time to assess each candidate. And they may be reviewing your resume on their Blackberry.
A 3-page (or longer) resume will probably be ignored completely. You can, and must, state your case within 2 pages.