Intervals / booking it

Back on the treadmill today for intervals.  23 minutes into it, my stomach was growling and I was feeling faint.  38 minutes into it, I was booking it at a 10 min / mile pace and my right foot doing its weird heavy thumper step.  40 minutes into it, I was happy to ease into my cooldown.  A few hours later, I'm happily slurping ice cream on the couch.