What Now?

I don't have another event in the near future so I don't have a training plan to follow. And if there's one thing I've learned in the past two years, it's that I need to have a plan. Right now, I'm a bit lost. I was thinking that I'd run for 30 minutes three times a week, do some ab and arm strength training twice a week, and a bike ride once a week. But I don't know how much I'm supposed to be running. Do I just keep doing it to go faster and farther in 30 minutes? Or will that wear me out and maybe even cause an injury? Do I just run for comfort, meaning if I feel good go for it and if it's a bad day just take it easy? Is it really as simple as just listening to my body? Then how do I improve if I don't push myself? I'm so confused!

Right now I'm on the MWF running schedule. I felt great on Monday so I did a 5K in my best time yet--33:24. But today I didn't feel as good and my pace was a little over 11 minute miles so I ran only 2 miles. Tomorrow I'll do my arm and abs exercises and we'll see what kind of run Friday brings.