Notes
As it turns out, running at a 4% incline is a lot harder than running at 0% incline. :)
I decided to get a baseline for my cardio capability, and, for the first time since I started running in January, ran at 0% incline instead of 4%. Turns out I can run a lot better at 0% - ran the whole 30 minutes, at 6.2 mph (9:40 pace), with the last 2 minutes at 6.5 and 7.0/7.5/8.0 mph, and finally made it to 5k (3.11 miles) exactly at 30 minutes. Yay! :)
So, I think I'll start doing 2 days a week of flat running, working on increasing my base cardio speed and duration (going to start increasing my running time beyond 30 minutes), and then 2 days a week continuing the incline/interval training at 4%+/7mph+