Do you mind if I ask how you monitored the distance? In order to cover 14 miles in 2.5 miles, you would have walk at the speed of 5.6 miles per hour, and that is a lot more than just a "brisk walk". You would have to run, or at least jog, to cover 5.6 miles in an hour.
I don't mean to be a PITA but maybe you are not correctly estimating the distance (and you may think that if you walked XX miles, you burned YY calories - and that's why I pointed it out).
I agree with mamaspank that anything is too big doses is not good. If you are just starting, you may soon develop shin splints or some other problems from doing too much too soon.
Dearest Schumeany: Yes, those are size 4 jeans hugging my posterior. Thank you for being such motivation!!!