Still, here's a little motivation your way: This year, I started running when it was minus 20 degrees centigrade. Overcast, cold, raining? That's just my kind of a vibe. :) Elaborate?It may be easier to be a person that doesn't drink soda than it is to be a person who doesn't want to drink soda.
For me, discipline is deciding once to be the type of person who runs three or four times a week. Motivation, for me, is deciding if today is a day I'm going to run. It's too easy for me to say no, not today, I'll run tomorrow instead. At times I don't want to run, but how I feel that day doesn't matter. I've decided I'm a runner, and my lack of motivation that day doesn't matter. I'm still going to run. Maybe that's a really narrow difference and doesn't work for you. We're all different, and what works for me may not change anything for you.