My goal when I started was 4.5 mi without walking, which died at about mile 2.5. Instead I made it to 4.0 mi without slowing, then dropped to 5.5 mi for the next quarter-mile, and down to 3.0 mph for the last quarter-mile. At about mile 3.8 the tunnel vision began to kick in along with the requisite urge to vomit. At mile 4.0 I decided to drop it down so that I didn’t get too fuzzy and trip or something else stupid, and when that didn’t significantly reduce the symptoms I dropped down to a walk.
I may not have met my goal, but I’m still mostly pleased with the run. My 5K time was just about 38 minutes, and I again made it to 4 mi without walking. That works for me. I still need to work on slowing down, though. My wife is convinced I’ll see a dramatic increase in distance if I just cruise at 5.0 instead of pushing to 5.5 or 5.7. While that may be so, I need to find something to distract me more thoroughly if I’m going to be okay with loping along at that speed.
(No offense intended, of course, to the people that like 5 mph, I’m just saying I get bored and distracted very quickly at that speed.)
Another thing I figured out with this run: if I crank up the resistance/grade on the treadmill for the walking part (first mile), then my calves don’t hurt when I get around to the running. My shins scream a bit during the walk, but it’s nowhere near as debilitating as it is the other way around. The wife still rolls her eyes at the fact that it takes a full mile for me to finish warming up and start actually jogging.