Need to switch gears

I mentioned in my last post that I’m done with 4 mile runs (or anything farther). I’ve never been a distance runner and only 10 or so 4 mile runs started to take its toll on me. I’ve developed a soreness on the inside of my ankle. I rested it up for a few days, then went back out yesterday for what was going to be a 3 mile jog. I felt the ankle a little and ended it at just 2 miles. The good news it was a fast 2 miles (9 minute per mile pace). The bad news is I need to rest up the ankle some more. The last thing I want it a nagging injury. Luckily I stopped when I did. That takes some discipline. My next run, for sure this time, will be intervals with sprinting. In the meantime, I’m going to give these a try:
100 pushups
200 situps

I started them last year but never finished.