Since you guys are giving some good advice to Ghost on training let me throw my hat in the ring.
I'm averaging 
31 miles a week, 10:09 pace. Basically I go "jog" 5-6 miles 3-4 times a week and do a long run on weekend increasing 1 mile/wk. This past Sunday was 13 miles. My running 
goal for the year is to do 12 halves, broke the 2hr mark on most recent one (8:46 pace), looking to get in 8:45 pace by summer, 8:30 pace by fall, and 8:00 pace by Jan '15. I have no running experience or training so these goals may be a little high or low.
So with the 
goal of increasing my pace, my question is should I incorporate tempo runs and intervals at same time or start with one for a few weeks to get adjusted and then incorporate the other. I'd like to keep the long run 
(increasing 1mi/wk) on the weekends until I get to 20 and then sign up for a full marathon sometime in the second half of year.
Part of me feels like a real big ##### for running so slow. I don't know if I'm just being lazy with myself or if that is just my natural pace. Like I said, never ran in high school or anything organized. I could stand to lose a little weight (6'0/195) and stop smoking/drinking so much, these would probably help my speed as well.
Thanks for any advice.
(Will probably sign up for the NM/TX half this Saturday, haven't done any prep other than getting in 30+ miles weekly and don't really have a goal for it, but I'd kinda like to participate in a running event this weekend. ETA: looks like my 8:46 pace would have garnered 2nd place in my age group last year, may have to go get a medal  

   ). Congrats to all who qualified for Boston this year and you three or four who will be there running.