Why does this feel like starting over?

I "officially" entered training for that whole half marathon thing about a week and a half ago. My first week was more of a free form attempt to ramp up my active days. My 2nd week was about trying to follow the program I picked out.

Successes this week:

1. Tracking my food - I've returned to the diligence of watching my diet and am back to where I was in the beginning of winter: 130.2 lbs.
2. Exercised 5/6 days so far including biking, running, intervals.
3. bought new swimsuits - 2 BIKINIS!
4. I signed up for a 10K in 3 weeks

Failures: -- luckily few, but warning: I may swear here

1. F*ck this is hard! 2.5 - 3 miles is really hard! I want to die/walk within minutes of starting. 
2. Strength training: I totally half butted it. 

I miss 5 miles being normal. I want to beat myself over the head for feeling that its a failure, that its hard again to run 3 miles, but its frustrating! It's like starting over and it sucks. 

But yes, in the grand scheme of things, this is going to be hard. 13.1 miles is not supposed to be easy or everyone would do it. So I'm going to stop whining now. I have 3.5 hours of free time before I need to get ready for work. Time for yard work!