Go short and go hard. Learn technique, then do it fast, then you can do it long!
There are a few things to look at as you are making the change over to CFE training. First, it is a complete paradigm shift in thinking. Even if you have done high intensity sprint workouts before there are differences with these workouts. There are no other programs that include all the aspects of CFE. Also the number of high intensity sprint workouts is most likely higher than you did in the past and on some days there are 2 high intensity workouts in the same day CF [CrossFit] and CFE [CrossFit Endurance]. Adding the strength and conditioning [CF] aspect on a consistent basis is another difference. These WOD’s hit all 4 energy pathways separately and together, establish / enhance neuromuscular and neuroendocrine responses which prepare you for a racing environment. There is an adjustment period in a few areas:
1.) Beginning to CrossFit
2.) Beginning CFE
3.) Beginning CF and CFE in the same day
* 3 – 4 month’s adaption is a good marker
CrossFit Endurance has plenty of elite level athletes who CrossFit more then they train for their sport. Your number one goal should be to CrossFit 4-6 times per week, 2nd goal is to have the ability to do 2-3 sport specific workouts per week. Tempo or Time Trial days should always be on a CrossFit rest day.
More is not better, and rest / recovery is the reason you get faster
In endurance training the traditional belief is that the more you run, the more efficient you will become. This is not correct! Studies show that running economy will be improved more through anaerobic training than endurance training.

Nutrition:
Keep an eye on your nutrition, if it’s not ON, get it dialed in! If you’re not already following a paleo or paleo Zone nutrition plan then it is highly recommended that you do so. Pay attention to your energy and if you need some more rest… Take IT! Getting your nutrition dialed will enable you to see a noticeable difference in your results as your body adjusts to having better fuel and how to use that fuel on a regular basis.
Your running is videotaped so YOU can see exactly what you are doing. What you are doing and what you think you are doing is not always the same thing. Seeing it adds another understanding / dimension to the experience.
You need to believe in the program and know that you are doing everything you need to do in order to improve.