I'm not sure if I've said anything publically about this, but I'm "thinking" about doing a marathon later in the summer or early fall. I know that for now the best thing I can do is start getting some extra time in on my feet.
My "training plan", based solely on what I think will work and therefore not subject to the rules and regulations of legitimate training programs, is to LENGTHEN my daily runs by increasing the walking interval while decreasing the running interval. The results of which will be longer training sessions that aren't likely to get me injured.
So, if I do a 4/1, 40 minute session I run for 32 minutes. If I do a 3/2 interval for 60 minutes I run for 36 minutes. Not that much difference but I get an additional 20 minutes of training.
Hey, that's my story and I'm sticking with it.
ORN: 60 minutes and 3/2 plus 10 minute walking warm up and 10 minute walking cool down. Total time, 1 hour 20 minutes.