Long Term Goal

So, I think I'm going to try running. I've thought about this for a while and listed it (run in a marathon, lose weight, etc) in my list of must do's before I die. Sometime before the school year ended, I had researched about half marathons and thought that I might want to train for several half marathons before I tried to run a full marathon. If, by next year, I see that I'm not ready, I'll continue doing 10K and half marathons in order to make sure that I'm ready to do a full marathon before October of the following year.

My long term goal is to run in the 8k Shamrock Shuffle at the end of March. 8k is approximately 4 miles (I looked it up). I've been researching some websites that offer beginning running programs and I'm going to start this weekend. My first week will consist of: a 10 minute walk, a 9 minute walk and a 1 minute run and getting to a 5 minute walk with a 1 minute run twice. If I make it through this week, I'm going to buy shoes. Or should I buy shoes first? I get paid next Friday, but want to start this running business soon. I'll see how my shoes hold up and if I'm uncomfortable or in pain, I'll buy some shoes. Now, if I'm not feeling up to increasing my runs the following week, I am free to continue the first week's program of 5 minute walk, 1 minute run twice for a few of those days. I just don't want to build up so fast that I'm really not able to keep up. So, first long term goal: run 4 miles for the Shamrock Shuffle by the end of March. (I'm not even worrying about how fast I'm going here, I just want to be able to do it).