Janviv

Finally at the 3rd attempt I managed to get through the 1st 3 minute run, I can manage the 2nd part of the run, but having breathing issues at the beginning of a run, due I think to age (66), mass (overweight), never having run before & Asthma. I am going to repeat Wk 3 & hope I can get through it, but will I cope with what comes next & why is my distance is getting shorter, I ended week 1 day 3 at just over 2 miles, but now I am doing 1.75, why?