reach my goal weight and stay there

I’ve just talked to a friend who is looking for a running partner. We’ve decided to go running 1-2 days a week, after class.
The only problem with this that I can see is that I’ll get bored with this, and start making excuses not to do it anymore within a month of starting.
I’ve got to come up with some sort of incentive for me to stay focused. Any ideas?

This term, I’ll be living a half hour walk from campus. So between walking and biking everywhere and finally not being in England (and binging on amazing deliciously unhealthy English food) I think I can pull it off!