I Have Endurance and Speed

I have endurance and speed, but I lack running stamina.  I can go long...marathon, 50K, 50 miles, 100K, even 100 miles...but it'll be painfully slow. I have short distance speed--5K easily under 20:00, but I can't carry my speed to longer distances.  I need to work on keeping a reasonable pace for a reasonable distance.

In my mind, the best combination of endurance and speed is the half-marathon.  That's where stamina wins out.  It's not pure speed, but you still need some quickness.  It's not really long, but you still need an endurance base.  I don't have any half-marathons on my racing schedule, but I can do some tempo-ish runs in that range. I'm thinking lots of 10-13 mile runs will do me more good than short intervals or long endurance runs. And I'm speaking as an ultramarathonn guy.  I definitely need the long runs, but those may naturally come in the races themselves.  I run enough ultras (8-10 per year) that I can probably keep a good endurance base going throughout the year with just those races. What I need is stamina. 

My master plan for the next 1-2 years is to set personal records at every race distance from 5K to 100 miles.  Ambitious...but possible.  Dream big!  To accomplish this feat, I need stamina. For the rest of this year, I will incorporate more 10-13 mile trail runs done at around marathon pace. I still have two ultramarathons this year too. The ultras will keep my endurance, the up-tempo medium runs will build stamina...and maybe I'll throw in a short race (5K or 10K) to test my speed. Good plan? 

2012 is going to be a GREAT YEAR.  Heck, the rest of 2011 is going to be great too.