Oh there are so many theories on this. So very very many.
I will put in a push for the percieved exertion method which is you should spend the BULK of your exercise at a range where you can talk smoothly but your breathing is very noticible - where any faster and talking would be effort and do intervals into the "can talk but really dont want to" arena.
Lost successfully, followed by a whole lot of setbacks. And then some more setbacks. Starting over.
Mini Goal #1 (4/27 - end of May)