I found a podcast to help me along the way. It's called C25K (which stands for couch to 5K). Basically the same premise that I have been doing with alternating running and walking, but what's great about it is that I don't have to time myself, because the guy tells you when to start running or walking. The first week in this program is 60s runs and 90s walks, so guess what? I graduated (I had been doing only 30s runs before this). It was harder than I thought but I got through it... I didn't have the energy to walk the extra time (the first week only calls for 30 min and I usually do more than that in my cardio workouts), but maybe I can go for a second walk later.
Not a bad start to the week!