You may want to consider downloading a couch to 5k program onto your cell phone. It's a 3-day-a-week, 8 week plan for running a 5k. There are a bunch of them out there. I tried to do it but it was causing problems with my fibromyalgia so now I've scaled back.

I, too, am motivated by how good I know it'll make me feel. Also motivated after already putting some time in and not wanting that work to go for naught.