I can't help it- I just like the speed podcasts because it's intervals so I did it again this morning. I do want to try stamina (but not yet!). However, having done speed, I found I was still feeeling pretty good so I thought I'd just carry on after the podcast finished and stop when I got to 5k. Didn't bother doing the intervals for this extra bit, just carried on at 155bpm which is my usual pace. Now I know that I can do 5k and actually put the pace up a bit in the middle by doing intervals and not wear myself out. Might try that next time, just run 5k without the podcast and see if I can do a few intervals.