Warrior Dash Training

So my husband and I signed up to do the Warrior Dash.  We are doing it with my brother, his wife, and a bunch of our friends.  If your not familiar with Warrior Dash here is a little taste of it:

Now when I watched this video I thought to myself now here is a race for me.  I can do the race and hydrate myself with beer after, that's right up my alley.  I think I overlooked a very important part of the day prior to signing up for this-the race itself.  I realize I am not fit.  Especially when my brother tells me often, how out of shape I am.  He is a real exercise nut.  He does P90x with a weighted vest on.  Now that is to hardcore for me.  My exercising over the last 8 months has consisted of doing leg lifts and by leg lifts I mean lifting my legs onto the coffee table while I watch crappy reality t.v.  I do work full time and go to school full time so I am not a total slug but exercise definitely isn't my favorite thing to do.  So I have downloaded two apps to help me get into shape, my fitness pal and couch to 5k.  I love both of these but I can not express how much I hate running.  When I run I feel like I am going to die each time.  A friend of mine loves to run and she talks about the "runners high," and her "second wind."  I believe both of these things are total bullshit.  Running feels to me more like what I imagine an overdose feels like, my heart about to explode and my lungs burning.  Also my shins always feel like they are going to snap.  This is probably because of my body type, which can best be described as a potato on a stick.  I have skinny muscular legs then a round body.  I am not huge by any means but I have a solid 20lbs to lose all from my mid section and I blame this on having kids.  I am hoping my workout gets easier with time because I want to get in shape and finish Warrior Dash to shove it in my brothers face.