4 Miles in 30 Minutes

Good morning folks.

I have searched this sub and Google just so I'm not being repetitive in the sub, but I can't seem to find a case like mine.

I am trying to run 4 miles in 30 minutes and I have seen most people saying go on longer runs, which I agree with. The longest I ran for 1 hour and 45 minutes and I felt great. I took a month/a little over a month off from running because life got busy quickly and now I'm struggling to run for 30 minutes straight again. I know that it's because I took some time off and I also know that if I keep up on it, my lung capacity/endurance will get back to where it was before the time off. That's not what I'm worried about...I'm worried about my pace. It's slow. Painfully slow and I've been running since May (minus the long break I took). Since May until now I've just focused on endurance and distance rather than speed so I've built up good endurance, but speed, not so much.

I've tried to search this sub and Google for training plans for my specific case but can't seem to find any. Any tips? I know to do interval/speed training but I'm not sure how to map out my training regimen nor am I aware of any apps that I don't have to pay for to help me along.

Any tips or FYIs would be great. TIA!