I started running last year, and was very apprehensive as the end of October approached, and the dark nights arrived. I was scared that all my hard work during the previous months would go out of the window because I wouldn't be able to run in the dark, by myself.
My solution was to make an arrangement with a running buddy. Once the commitment was there it was easier to stick to it. Each of us would feel we were letting the other down if we cancelled. And generally (aside from the weeks during the thickest of snow), we have kept it up. Running in the dark is not a problem, we both bought bright yellow jackets - the fear was all in our heads.
It is mainly a mind over matter issue - and once you have your first run in the bag, even if it is slower and shorter than you could manage previously, it should be all downhill.