I am a heel striker

I am a heel striker, and I want to reform my ways.  For a while, I didn't know that I wasn't using proper technique.  I just ran;  it felt natural.   Then I noticed friends reading and raving about "Born to Run" and buying minimalist shoes.  Finally, I read the book and bought the shoes.  After that, I didn't change anything because it would have taken time to learn something new, and I didn't want slowing down to affect my chances of qualifying for Boston.  It's time now.    

How does one learn to run properly, and not just study how, but practice by doing drills, adjusting, adapting, and ultimately, run more efficiently?   I am about to find out how difficult it is and how long it takes.   Today after my speed work and while folding laundry, I watched "Evolution Running," a 45 -minute DVD that teaches how to become a more efficient runner.  It was straightforward, and most of it made sense.  I  have more information to read and drills to try.  If I feel I am already running naturally, and I am not, how difficult will it be to retrain myself to a new normal?  It seems daunting.   My motivator is that if I can run with the proper technique, it should be easier to run, and I might even be faster.  That sounds too good not to try.