Hey stephy. I think instead of "thinking about it" you need to make a conscious decision to "Just do it". Change one thing. If you currently don't eat breakfast, try eating breakfast for a week. If you can, try and fit in a 30 minute walk every day for a week. Just do one small thing at a time, and get used to gradually changing for the healthier. I think the task can be overwhelming if you look at the big picture.
Make a small acheivable goal to start off with, like getting in your exercise, or cutting back on the candy bars for just one week, or even one day. Once you have a small success it will motivate you to be successful again and again.
And if you do slip up, and you will, then just get back to what you know is healthy.
Also, come back here often and post about your day.