It's always so hard

So since I verbally commited to doing the Pasadena Half (maybe full but doubt it) Marathon, I guess I'd better train.

Tonight-Speedwork. I HATE speedwork, so I guess I'd better suck it up and do it.
8 x 400M 90 second recovery @ 2:15 target.

Lap 1-1:55 (yeah)
Lap 2-1:56 (cool-and still no pain in my knee)
Lap 3-2:06 (still ok)
Lap 4: 2:05 (starting to feel tired)
Lap 5: 2:10 (WHAT?!?)
Lap 6: 2:12 (this is starting to suck)
Lap 7: 2:13 (OK now I'm sucking wind)
Lap 8: 2:16 (Thank god it's over!!)

Oh-I just re-looked at the pace chart. At a 2:15 target, that would give me a 4:54 marathon, 5K race-30 minutes. I've been trying for a sub-30 5K so I better move my pace target to 2:10. I've been close, but have not been able to break that sub-30 5K. Looking at my lap times, I was able to do the first 5 laps at that pace. It's the last 3 when I get tired that I can't sustain that pace. Gotta work on that. Gotta increase the cardio. Can I blame the slower pace on the 175 situps and 140 burpees I did yesterday? HMMM maybe not. That's just an excuse I guess.