Following a running plan!!

I'am currently following a RW half marathon running plan (sub 1:25) and was wondering if someone could answer a question?

Running the miles doesn't seem to be a problem but sticking to some of the repeats do.

On different runs i can manage some repeats but not all. eg- 6/7miles inc 4x5mins fast 4x5mins slow

Does anyone else experience this? 

You're probably running your repeats a bit too fast.  You need to pace them so you finish the last one at about the same pace, or faster, than the others.  If you put a recent race time in here http://www.mcmillanrunning.com/index.php/calcUsage/calculate

then it will tell you what paces you should be running for which sessions.  Is this your first Half?  1.25 is a fairly ambitious target for a first timer if so.  How are you coping with the mileage?  

What does the plan class as fast. Is it 5k pace or 10k pace? I used the RW garmin ready sub 1:25 plan for a while, and fast was approx 6min/mile. I can do a 1:25 HM, but struggle to hit sub 6min miles in intervals. The plans mile times for 'fast' is
Fast (5k) 5:57
Fast (10k) 6:15

I'm now using Mcmillan for paces. For a 1:25 HM , Mcmillan recommends mile intervals of 6:01 - 6:12 - pretty much in line with RW. Still find this quick for me, but I am improving gradually over time with my speed. Intervals are my toughest session and often want to quit midway through. Its a bit of a psychological battle. Not running the first interval too hard is important for me.

What pace are you running these interval?

Sorry about the delayed reply guys.  I have been away recently and not had chance to post back until now.

I really appreciate the feed back about the interval running and im going to look at the Mcmillan site for paces.

I have ran a few half marathons already with my 1st outing timed at 1:32.48 and my current best being 1:27.58 with this advise i will hopefully crack 1:25?