Want to train for a half-marathon in May

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I have wanted to do this for years. I have always been too busy. My kids are finally at an age that I can take the time to get out there and train. One of my biggest worries is when I have tried to run longer distances in the past, I get BORED. Music does not help. And I have to pee once I hit the 3-mile mark. I am doing this with a couple of friends, which I think will help. However, I have tried to work out with friends before and they flake out on me. So with or without their companionship, I want to do this.

Any advice to keep motivated when I hit the 5-6 mile mark and beyond. I run/walk 3 miles regularly and I can walk for 5-7 miles without any problems. I am looking forward to this, yet dreading it.