Running Nerves

So last week while I was in Boston, I ran about two times. I was proud of myself for this even though I should have ran three times. When I got back, I quickly became lazy and found every excuse possible to not run:

"I have to unpack."

"I have to study."

"I need to rest."

Today I finally got back into it and chose the treadmill because of the messy snow outside. I had to run for 24 minutes, then walk 1 minute, and then 24 again. I finished the 24 but it was rough. When I attempted the second 24 I felt like I couldn't do it. It's strange because I know my body could do it but I think my nerves got the best of me. Now that I'm almost halfway done with my training I am starting to get nervous...

Very nervous.

I'm guessing it's because at this point last year, I realized I may not be able to do this because of my injury's and other bad luck. At this time last year I went downhill.

Runners: Do your nerves ever get the best of you? Any advice?