The first interval session: a 1 mile / 2 km fast run, non-stop, repeated 3 times in total. Three fast miles, each run continuously, with a recovery between them. The card does not specify the rest - take what you need to run the next one properly, walking or jogging easily until the breathing has settled.
Intervals are how the program builds speed it could not build in one piece. One fast mile is hard; three fast miles in a row would be a race; three fast miles with recovery between them is a session, and it teaches the legs to run quickly when they are already tired, which is what the last 10 km of a marathon is made of. Fast here means the effort of Day 34's 2-mile run, or a little quicker - a few words at a time, not a conversation.
Warm up with ten minutes of easy jogging and a few short pick-ups. Run the first mile controlled rather than flat out, so the third is still a fast mile and not a survival jog. Note each mile's time - the spread between them tells you how well you paced it. Cool down with ten minutes of easy jogging.
Three fast miles with recoveries between them - the program has started teaching speed in pieces.
Make it Harder: Run the three repeats with the same recovery each time, and make the third the fastest of the three.
Make it Easier: Run the repeats at a brisk rather than fast pace and take as long as you need between them.
