I'm also a former smoker and had abused my body over the past couple of years from too many kebabs and heavy nights out, i was totally out of shape.
I have spent the past year trying to correct my body and up until the past month have been going to the gym nearly everyday, running 1.5's on the treadmill, swimming laps, rowing, circuits, etc... i have only stopped now because i am comfortable with my bodys appearance and strength and feel the only things i need to do now is eat properly and exercise reguarly but not over the top, couple of runs, press ups + sit ups mon - weds - friday etc while i am in the process of moving back to Portsmouth to start my application, once i have a date set for my PRMC its turbo time... i wouldnt bother going mental until you have a date set, if you have good general fitness it shouldnt be hard to get to PRMC level in say 2 months?
but everyone is different.