My "Bread & Butter" Workout

I had to look this phrase up because Bread and Butter is certainly not a staple in our house, but you know what is??? Progression Long Runs.

The art of a Progression run is honed over time, the key is to not be too aggressive too early. I suggest you choose a flat-ish route. Start out at your normal easy pace, and with each mile, increase the effort a little notch, so by the time you hit half way, you're starting to focus, and by the final mile, you are working pretty hard. I like to do these at least once a month throughout a training segment with increasing distance to see progress. When my fitness comes around, it shines through and I have confidence going into my next race! Here are my splits for yesterday's long run.

DATA: 16mi Progression, 1mi Cool Down.
1-7:58, 2-7:14, 3-7:02, 4-6:57, 5-6:46, 6-6:44, 7-6:37, 8-6:31, 9-6:27, 10-6:20, 11-6:12, 12-6:03, 13-5:54, 14-5:44, 15-5:34, 16-5:17, 17-7:05.
Total Time: 1:50
Avg Pace: 6:30/mi

What is the workout that helps you know you're fit and ready for your goals?