Alright! So natural intervals are probably my favorite speed work out ever. If any one wants to meet me to do some of these bad boys I will be hitting the Happy Jack trails at 5:00pm this evening. I will start from the Tie sighting parking lot. Bring a set of poles. If not here is a break down on how they work: Natural intervals mean that you do your intervals as you do a run. So... You leave on a running loop and after you've warmed up for 20-30 minutes you do the first interval. You try to do your intervals on uphills, so the length of the interval varies with the length of the hill. You may do a hill that is 30 seconds or you may do a hill that is 3 minutes, it doesn't matter just run the uphill from the bottom all the way OVER the top. Try to vary the length of the hi...