Just in case you were wondering: I didn’t die.
I did run intervals per the last post, but I discovered that 8.0 on the treadmill is not meant for me. I’m pretty sure whoever wrote the intervals was not 5’3″.
I alternated 4.9/5.0 and 5.9/6.0 and then ran at 5.0 for the 5 minute stint. Really focused on exaggerating my breathing to get into the deep breathing and train my muscles (shallow breathing = bad, apparently.)
Definitely felt worked out after this.